
Once again, we need to Qualify the Issue. What exactly is the problem with your e-mail? Can you not send, can you not receive? Are neither working? Are you having problems with duplicate e-mails or is the e-mail just endlessly checking and then timing out? These are the most common issues and have the same basic steps, regardless of the e-mail client you're using.
If you're getting problems such as your e-mail program giving you an error and then physically closing (crashing), then there's some form of file corruption that needs to be addressed, which is outside of the scope of this guide. The challenge is that there are just too many things that can go wrong and too many possible fixes to cover in a simple guide. Unlike browser troubleshooting which has a few common problems, e-mail program issues are far more complex and varied.
Remember, this is not intended to be all encompassing. It's designed to give you the most basic, common steps to try to resolve the issues yourself. These steps have been compiled from taking tens of thousands of calls on the subject and managing departments in multiple organizations that have taken literally hundreds of thousands of similar calls. Needless to say, some patterns developed over time.
What Is An E-Mail Client & What Is Yours?
People don't always understand the difference between their browser and their e-mail program. For some, e-mail is the only thing they will ever touch on the Internet, aside from the occasional animated greeting card from a family member. For others still, they've never opened an e-mail client and only ever access their e-mail through their browser, so they don't know the difference. That's why we need to clarify.
If you check your e-mail through your browser, then you're using Webmail. Your browser is the same program you use to go to websites. GMail and HoTMaiL are examples of services that use a Webmail interface by default. If that's how you're getting e-mail, then the troubleshooting in this particular guide isn't for you.
First of all, web-based e-mail rarely goes down and even if it does, it's not likely a problem on your end, unless your browser is acting up. You can also do some Browser troubleshooting, if you suspect that is the problem. Otherwise, Webmail issues are probably a very short-lived issue with the e-mail provider. Give it a few minutes and whatever issue you had will likely be resolved. If not, contact them.
Still confused? Below you can see screenshots of HoTMaiL and GMail. As you can see, both sites are loaded inside a browser because the top of the window shows all the toolbars, address bar and buttons that you would see when in your browser, surfing web pages. An e-mail client on the other hand, is a program dedicated to e-mail and has a much more specific layout.


The vast majority of people who use Windows rely on whatever e-mail program came with their Operating System. In Windows XP this was Outlook Express. In Vista, this was Windows Mail. With Windows 7, Microsoft stopped including an e-mail client with their Operating System. However, most OEM manufacturers, such as Dell, HP or Acer, will include software on the computer by default. As a result, most customers will end up with Microsoft's latest e-mail client, which is a vast improvement of their previous incarnations: Windows Live Mail. Here are quick snapshots of each, so that you can see what they look like. We have Outlook Express first, Windows Mail next and finally, Windows Live Mail:



The basic functionality of each of these e-mail programs is similar and sadly, they also suffer from some very similar issues, but let's not get ahead of ourselves. Down the left column you will usually see the folders and contacts. In the main body of the program you will see the list of e-mails and below that is usually a preview pane, wherein you can read your e-mails. Of course, these views are customizable, but this is the default layout. The menus and options are very similar as well, but of course, each subsequent version has more to offer, such as better filtering, SPAM and Phishing protection.
In fact, if you're on Windows XP or Vista and are still using the original e-mail clients, it's highly recommended that you upgrade to Windows Live Mail. It won't take you very long to adapt to the new program, no matter how technophobic you are and the installation wizard will walk you through migrating all of your e-mails and contacts into the new program.
The problem of course, with using Outlook Express for example, is that it's essentially a decade old program and as such, it has flaws and limitations that will always exist. In fact, Microsoft stopped writing patches and fixes for it many years ago. So, like a lame horse, it's time to put it out of its misery and move on. Here's the link to download Windows Live Essentials.
Thunderbird, Microsoft Office Outlook & Everything Else…
There are dozens of free e-mail clients out there and some that are not so free. Microsoft's Office Outlook will cost you a pretty penny, but it's far more than just an e-mail client. It's a full PIM (Personal Information Manager) with calendar and contacts integration and a whole slew of features you won't find in most other alternatives. One of the really annoying things about Outlook though, is how much it keeps changing. Don't get me wrong, change is good, but they move things around a lot. Just take a look at the differences between Outlook 2007 and it's next version, 2010 below. The ribbon changes everything. It takes some getting used to.


Then, you've got the other odd one's like Eudora and Incredimail, which are basically like Outlook Express on crack. They're a waste of time, in my opinion, but some people like them. To be honest, when I receive an e-mail with wallpapers and animated icons and little dancing squirrels or babies on the bottom it makes me cringe. Whatever, each to their own.
The last e-mail client worth mentioning is Thunderbird. It's Mozilla's alternative to Office Outlook and it is quite nice. Remember, Mozilla are the guys responsible for bringing your Firefox, the major competition for Internet Explorer as a web browser. Once you add the Lightning plug-in to Thunderbird, you even get calendar integration. So, it's a very nice e-mail program with support for IMAP as well as POP, which is not something all of them support. Again, that's a topic for a different discussion. Here's a shot of Thunderbird, with and without the calendar add-on:


So, now that you know what an e-mail client is and you've probably picked out the one you're using, let's continue.
The Problems
Let's break this down into the most common issues:
- Can't receive e-mail, but can send
- Can't send, but can receive
- Can't send/receive e-mail
- E-mail locks up or takes forever when sending/receiving
- Getting the same e-mails over and over again
- Getting every e-mail exactly the same number of times, usually 2 or 3
With any of these problems you may or may not get an error code. Microsoft specifically loves to give cryptic messages mentioning things like SSL, even if you haven't enabled that feature. I've even found this site dedicated to determining the resolutions for each one of those codes: www.0x800CCC.com. Often though, they're useless messages. I've actually found that it's usually quicker to ignore the 0x800 messages and try the same basic troubleshooting steps. By doing so you can fix almost every e-mail problem a person will encounter.
Things To Try Every Time
- Restart. I can't tell you how many times there have been quirky e-mail problems that just disappear after restarting either the e-mail program or the whole computer.
- Disable your Anti-Virus or Firewall. In almost every problem with e-mail, your Anti-Virus or Firewall could be blocking or slowing you down, even if it was working fine 5 minutes ago. You can go here to find out how to turn e-mail protection off, to test this theory. You might need to restart your e-mail program in order to make those changes take effect. Now, try your e-mail again. If the problem has gone away, you found the culprit. Wait for the next update to the offending software before re-enabling it. This is likely a temporary problem that they will find and fix in their next update. It's quite common.
- Retype your E-Mail Address. Unless you've been told otherwise, it's a good idea to use your full e-mail address for the Username. So, if your e-mail address is moc.erehwemos|bob#moc.erehwemos|bob and the login box appears with only bob in the Username field, then replace it with your whole e-mail address to see if it makes a difference.
- Retype the Password. If you get a login box, retype your Password, even if you haven't changed anything. This information occassionally gets lost or corrupted within Windows. So, it can't hurt. Passwords are always case-sensitive.
If none of those problems fixed your issue, then look at the solutions below. You might be able to find a more suitable solution.
Everyone Has Webmail
I have yet to see an ISP that doesn't offer free Webmail with their service. So, if your e-mail address is moc.erehwemos|bob#moc.erehwemos|bob, then your Webmail site is probably http://webmail.somewhere.com. This is necessary to know, because for almost all troubleshooting, you're going to verify if the account is actually working properly by checking it in Webmail, as well as in your e-mail program. You would log into your Webmail account using your E-Mail Address and the Password associated with that address. It's that simple. You can always check with your ISP if you're unsure.
Can't Receive E-Mail
It's possible you have an e-mail that's either too large and it's getting stuck while trying to download or there's an e-mail that's damaged on the server. Log into your Webmail service and move all of the e-mails from your Webmail Inbox to another folder. You might need to create a new folder before moving them, or you could use the Drafts folder. That's a common folder on most Webmail services, that rarely gets used.
Next, send yourself a test e-mail from the Webmail interface and wait a couple minutes for it to arrive. You probably have to refresh the Inbox to see it. Did it work? Did you receive it? If not, call your ISP. Your e-mail account may be damaged.
If it did work, then try moving some of those e-mails back, in groups of three or four at a time. After each group, update your e-mail program to get the new mail, usually by clicking Get Mail or Send/Receive. As each group successfully downloads, move a few more e-mails back until you find the specific e-mail that is the problem. Once you've narrowed it down, read that e-mail, if you can and Delete it.
If these steps didn't fix the issue, proceed to the Can't Send/Receive section.
Can't Send E-Mail
The first question to ask is, are you at home? Relax, I'm not going to call you. The point is, you pay for Internet at your home, which is likely the e-mail address with which you're having difficulties. While e-mail is portable, it's not always a simple process. Let me explain. If you pay for Internet with company ABC and then go to work, where they pay for Internet with company XYZ and you try to send e-mail from your home e-mail account, it may not work. You can probably receive your e-mail without issue, but sending requires some adjustments. Thanks to SPAMmers, ISP's have had to tighten the restrictions of their e-mail service. What this means for you is that in order to send e-mail using your home e-mail account's Outgoing Server, when you're not actually online with them at that exact moment, you have to prove you are who you say you are by logging in, first. It sounds complicated, but it's not that bad. Here's what you'll likely need to do:
- In your e-mail program, open your Account Properties. Depending on what program you use, you'll need to find the place where the e-mail accounts are configured. Usually, there's a Tools menu and an Accounts/Account Settings option from which to choose.
- If asked whether to Add a new e-mail account or View or change existing e-mail accounts, we want to View or change existing e-mail accounts.
- If there are tabs along the top of E-Mail Accounts/Internet Accounts window that you opened, look for a Mail tab and click that. This is where we'll find all of the e-mail accounts that are setup in this program.
- Usually, you can just double-click an account to open it's Properties window. If you see an option that says More Settings… click on that.
- There's two settings we actually want to check or adjust. The first is Authentication. So, look for the Servers or Outgoing Servers tab and ensure that My server requires authentication is checked. If the option is presented to you, tell the program to use the same information as your Incoming Server.
- Now, let's go to the Advanced tab. Here you will see the Port settings for your Incoming and Outgoing Servers. For most ISP's the Outgoing Port (SMTP) defaults to 25. If it's not 25, then write down the Port number, in case you need to undo these changes. In order to make Outbound Authentication work, change this Port to 587. Apply the changes, close and reopen your e-mail program and try to send e-mail again.
For a quick reference, here's how the Outbound Authentication and SMTP Port screens look in Windows Live Mail:


Note: Do not change the settings for Requires Secure Password Authentication (SPA) or anything that mentions SSL. These sound similar but are not the settings you want to adjust.
What you've basically done is had your computer call your ISP and have a conversation that goes something like this, "Hey, I want to send this e-mail."
You ISP replied with, "Okay, you look familiar, but how do I know it's really you? Can you prove it? You're not calling me from where you normally do."
"Oh right, sorry about that. Here's my Username and my Password and we'll use the side door, which is reserved for travellers like me."
Your ISP smiles and lets you go about your business and everyone is happy. Oh frabjous day.
That's it! This should solve your problem, but if not, proceed to the Can't Send/Receive section, instead.
Can't Send/Receive E-Mail
Don't overlook the obvious. Is there an e-mail outage? Check. If your provider has an outage page, check it. If they leave messages on their automated phone system, check that. Does any of your e-mail accounts with that same provider work on any of your other computers or devices? If not, then it's likely an outage. Wait it out for a while before calling your provider. It may recover quickly. Otherwise, let's continue.
If sending and receiving isn't working properly, we're not going to spend a lot of time messing around with settings. Chances are they're right and your e-mail account still won't work properly unless we Delete and Recreate it.
In the real world, things break and there isn't necessarily a known reason. Deal with it. You know those SSL errors you're getting and the 0x800 errors that have a paragraph of explanation as well as pages of troubleshooting on Microsoft's site? Well, we're probably going to ignore those, too.
That last statement probably just gave call center auditors a heart attack. Keep in mind though, that I'm not just speaking from personal experience, but also from the experience of all the teams I've managed through the years, as well. We're talking about hundreds of thousands of calls.
Just Fix It!
All a person is really interested in is getting their e-mail program working again and fast. So, that's what we're going to do. First, we'll give the e-mail settings a quick once over, retype the Password and try again. If that doesn't work, we're probably going to to just Delete and Rebuild the e-mail account.
Thunderbird and Windows Live Mail though, provide an extra challenge.
Mozilla knows how to make e-mail programs work properly, but before Deleting and Rebuilding an e-mail account, you have to move the e-mails stored in that account. It's very annoying that you have to do this, but because Thunderbird is far more stable than other e-mail clients, it's extremely rare you have to worry about it, anyway. I personally don't use Thunderbird, but I appreciate that it is one of the best choices for e-mail clients.
Second, there's Windows Live Mail. Microsoft used to be smarter than this. E-Mail accounts and the e-mails stored on the computer used to be completely separate entities. So, when you Delete and Recreate an e-mail account in any Microsoft program, the e-mails remain. Enter Windows Live Mail. Microsoft caught a case of the dumb. In Windows Live Mail and only Windows Live Mail, you now have to move the e-mails somewhere safe before you Delete and Recreate the account. Then you can move them back. I think they're taking lessons from Apple, because all of their e-mail programs are like that and on iOS devices, you have to Rebuild accounts constantly.
Check The Settings
This particular part of the guide is going to be very high level, because it would be far too involved to cover the settings screens for every e-mail client. Instead, I'm going to tell you what to look for and how to find common mistakes.
Where Do I Find My Server Information?
The first thinng you need to know is your E-Mail Server Settings. If you don't know them, Google them. Our friend moc.erehwemos|bob#moc.erehwemos|bob for example, would search for "somewhere.com e-mail servers". The first link that appears will contain the information you're looking for 99% of the time.
Let's assume that we searched for somewhere.com Server Settings and found the following information:
POP Server: pop.somewhere.com
Port: 110
SMTP Server: smtp.somewhere.com
Port: 25
Those are pretty common settings and the defaults for any e-mail program you setup. The POP Server is your Incoming Mail Server and the SMTP Server is your Outgoing Server. An easy way to remember this is that SMTP can stand for "send mail to people". That's not actually what the acronym means, but it's a convenient memory tool.
You may however, also see settings like the following:
IMAP Server: imap.somewhere.com
Port: 143
What is IMAP?
IMAP is an alternative method of obtaining e-mail to using POP. The difference between the two is that when you use POP e-mail, it is intended to be downloaded and deleted from the server once the computer has a copy of it. Whereas, with IMAP e-mail, the intent is to download your e-mails from the server to your computer, but leave all of the e-mails on the server, so that it can be managed from there. The benefit of IMAP over POP is that you can create folders on the e-mail server and move e-mails around inside those folders, rather than creating those folders on your computer, like you probably do now. If you want to check your e-mail from multiple computers, like a home and work PC, then whatever is on one computer will be the same on the other computer, because e-mail is synchronized with the e-mail server, rather than removed from it.
Who Uses IMAP?
Hotmail and GMail accounts are examples of IMAP services, and so is the Webmail service that is probably available through your own ISP. That is why, wherever you log into your HoTMaiL account, the same e-mails appear, because they are independent of the PC viewing them.
iOS devices, such as iPhones, iPads and iPods all use IMAP e-mail by default, if it's available. So do Blackberry devices and Mozilla's Thunderbird e-mail client. Ironically, IMAP e-mail has been around for a very long time, but only with the advent of cloud computing and smarter portable devices, has it really started to be used.
Setting up IMAP however, is not that much different from setting up POP e-mail. You still need to know the Server names and the Port numbers.
The previous examples provided explain what you might find when you conduct a Google search for e-mail settings. However, here is a far more comprehensive guide to e-mail and Server defaults.
Server Type | Common Prefixes | Common Ports | Ports with SSL Enabled |
---|---|---|---|
Any | |||
HTTP | 80 | 443 | |
POP | pop | 110 | 995 |
IMAP | imap | 143 | 993, 585 |
SMTP | smtp | 25 | 465 (587 with Outbound Authentication) |
From the table above we can determine that the most likely outgoing settings you would use for moc.erehwemos|bob#moc.erehwemos|bob would be the following:
SMTP Server: smtp.somewhere.com (or quite possibly mail.somewhere.com)
Port: 25 (465 with SSL enabled or 587 with Outbound Authentication enabled)
Of course, there are other Ports that can be used, and other names. This is by no means a foolproof method, but most ISP's stick to the standards.
Finally, it's worth mentioning settings you rarely see in action. People often turn these on, because they sound good, like they'll add an extra layer of protection, despite not knowing what they do or if they're supported. Of course, if your ISP doesn't actually have a feature provisioned for your e-mail service, enabling unsupported features will just mean that your e-mail won't work. Here's some examples:
Secure Password Authentication (SPA): This should not be confused with either SSL (Secure Sockets Layer) or Outbound Authentication. SPA is in fact, another higher form of security for e-mail services, but few e-mail providers or ISP's support it. So, don't turn this on unless you know it's available.
Authenticated POP (APOP): Similarly, APOP is not often supported. Depending on your e-mail client, you may instead need to choose one of the following forms of encrypted connection: None, Clear Text, Plain Text, Unencrypted, Password Transmitted Insecurely or Normal Password. Those will work with most connections, instead of APOP. If you don't see any of these options, then you don't need to worry about it. Just don't enable the APOP feature unless you're sure your provider supports it.
STARTTLS/TLS: Here's an option that actually is supported often, but it only works in certain e-mail programs. Thunderbird and Outlook 2007+ support this form of encryption, but most older e-mail programs do not. Check with your provider before enabling. It's not quite the same as SSL, but similar.
Certificates: Finally, we come to security certificates. If you know what these are, then you wouldn't likely be referring to this guide, in the first place. Every e-mail client that I'm aware of supports them and every provider does as well, but they're an after market product. In other words, you have to find a third-party certificate authourity, obtain a certificate and then you can configure it within your e-mail client. That is well outside the scope of anything we're going to cover. In other words, don't touch this.
The Steps
Those are the basics. Hopefully you now have a better understanding behind what you should use for your own e-mail settings. Now, just verify those settings inside your e-mail program.
- Usually you open Tools and then Accounts/Account Settings in order to gain access to the e-mail account properties.
- Find the account with which you're experiencing difficulties and view, change or edit the Properties of that e-mail account.
- If there are tabs, check each of them for relevant information as already discussed here. If you run into something we haven't discussed, then leave it alone.
- If there is a More Settings… button, you will need to click that to get to the rest of the relevant settings.
- Verify your E-Mail Address is spelled correctly. Don't use spaces, make sure the dots "." are actually dots and not commas.
- Retype your Password. Retype your Password. Retype your Password. In other words, even if you're sure you've got the correct Password, erase and retype it. Windows will frequently corrupt Password data, for no apparent reason. So, retype your Password.
- Verify your E-Mail Server names are correct. Again, look for typos.
- Make sure relevant security options like Outbound Authentication are only enabled if supported.
- Ensure you're using the correct Port numbers and encryption type if relevant.
- If you've made any changes to your account, Apply them, test the settings if there is a feature to do so, or by sending yourself a test e-mail and ensuring you can send and receive once again.
Once you've done all that, if you made any corrections, your e-mail is hopefully working now. If not, don't be too surprised. Like I said, in Windows, e-mail clients frequently corrupt e-mail settings for no apparent reason. You may have changed nothing and yet, your e-mail account suddenly stopped working. Don't blame your provider. They may not have done anything, either. It's very likely something gone astray within Windows. So, it's time to move on to the next section.
Rebuild The Account
It's taken a long time to get here, but this is usually one of the fastest fixes for any broken e-mail. When taking someone through e-mail troubleshooting, I usually Rebuild their account about 2 minutes into the process and it fixes far more problems than it doesn't.
You May Need To Move Your E-Mails First
- This isn't relevant for IMAP e-mails, because those are already stored on the server. You only have to worry about this if you've setup your e-mail account as POP, which is the default for most e-mail services.
- As previously mentioned, if you use Windows Live Mail or Thunderbird, you need to first move the e-mails and folders you want to keep to another location. All Mac e-mail programs have been designed the same way. It's a silly design.
- Your e-mail program will have a Local Folders or Storage Folders section. In Windows Live Mail, you may have to click View and then click on Storage Folders in order to enable that location, first.
- Right-click on that heading and choose New Folder to create new folders within that section. Create as many as you need. Then, you can then drag & drop your e-mails their original locations to these new folders.
Let's Start Fresh
Okay, so you've either moved your e-mails that you wanted to keep to a different location, or you don't need to worry about it because you're using IMAP or an e-mail program that doesn't join the e-mails specifically to the account.
- If you haven't already found the Server Settings, you may need to call your ISP to obtain them.
- Open your Account Properties, locate the correct account and Delete it. Make sure you're removing the right account.
- Now, just Recreate it, entering all of the necessary information, including:
- E-mail Address
- your Username, which is usually just your E-mail Address
- the Password
- the Incoming and Outgoing Server names
- You may also need to enable SSL, Outbound Authentication and adjust Port numbers, depending on your provider.
Save the settings and check the e-mail account by sending yourself a test e-mail. If it sends and receives now, then you've solved the problem. Rebuilding the account will fix e-mail problems more than 90% of the time.
If it didn't, then keep reading.
Repair Your E-Mail Program, If You Can
If you've made it this far and you're still not having any success it's quite possible something is corrupted. There are too many possibilities of what could be wrong and why, but depending on the specific issue here's an idea of what you might have to do next:
- Outlook has a couple hidden utilities: ScanPST and ScanOST to repair e-mail data files.
- Recently, they also released their Oversized PST & OST Crop Tool.
- Outlook also has a self-diagnostic tool. In older versions you would click on Help and then Detect & Repair… I'll discuss newer versions later.
- For Outlook Express you sometimes have to move everything from your Inbox or Outbox and then Delete the Inbox.dbx or Outbox.dbx files and restart the program. Other e-mail programs often recommend similar steps in order to recover from e-mail problems.
Start Googling Again
This would be one of those rare cases where you would actually want to refer to those 0x800 codes. Search Google for 2 or 3 recommendations about how to resolve your exact issue. Never rely on just one. Also, you can use www.0x800CCC.com to find specific solutions.
Reinstall The E-Mail Program
If you can't find a Detect & Repair… feature in Outlook or an Office Diagnostics tool in the Start Menu, under All Programs and probably Microsoft Office, then you will have to go to the Control Panel and run it from there.
- In XP you would go to Add/Remove Programs and run the Uninstall for Microsoft Outlook/Office.
- In Vista and beyond, you open Programs & Features and do the same.
Of course, you're not actually going to uninstall Outlook, but when you run the Uninstall program, it will ask you if you want to Uninstall, Repair or Reinstall the software. You will choose either Repair or Reinstall. Reboot once it's done and test your e-mail once again by sending and receiving a test e-mail.
For all other e-mail programs, you can probably just download the latest version and Reinstall the software over top of the current installation. This often fixes the problem. It's usually a good idea to reboot after you've done that, before sending and receiving another test e-mail.
If none of this has worked, you should call your ISP or maybe even a technician.
E-Mail Locks Up Or Takes Forever When Sending/Receiving
We expect e-mail to work instantaneously. Of course, that's not always the reality. Here's a few things that may help solve or workaround the issue.
Back Up A Minute
By now, you would have already turned off your Anti-Virus or Firewall software to see if that fixed the problem, right? If not, then go back to the Things To Try Every Time before continuing.
Check Your Outbox
Since that didn't work, let's make sure there isn't a problem e-mail in your Outbox. Move everything from your e-mail program's Outbox to the Drafts folder temporarily and send yourself a simple test message. If the test e-mail works fast, then move the other e-mails back one by one until you figure out which one is problematic. Delete and Recreate that e-mail.
Server TimeOuts
If you keep getting timeout errors, then your ISP is probably having server issues. If this happens frequently, then this workaround will eliminate the errors, but not the delays. We're going to change the Server Timeouts in your e-mail program. Open the Account Properties and in the Advanced section you should find a Server Timeouts option. Slide that up to two or three minutes and Apply the settings.

Microsoft Outlook Seems To Have A Problem
If your e-mail program freezes completely when trying to Send/Receive, you're likely using Outlook. Sorry, but Microsoft seems to have some real problems with handling e-mail. Yes, you read that correctly. If you're using Outlook 2007 or later, Outlook is known to freeze solid when checking e-mail. Complain to Microsoft and maybe they'll fix it, eventually. No other e-mail program seems to completely lock up the same way.
Is there a viable solution? Unfortunately, no. Replace Outlook with something else if it's really bad. Older versions of Outlook don't seem to suffer from this problem and neither do any other e-mail clients, including other Microsoft products. So, it's something new they've done that causes the problem. I'm sorry if you were expecting a better solution than me pointing an accusing finger at the software developers, but in this case, it's well deserved. If you don't believe me, then Google search for "Outlook 2003 freezes" and you get about 400,000 results, but for Outlook 2007 that jumps to 1.8 million and for 2010 it's over 4 million hits. Sure, this could be because older links are being deleted from the Internet over time, but Outlook 2007 isn't that old and it has less than half the hits. I think it more likely that the problem is getting worse. I've seen it in action hundreds of times and as of August, 2011 I'm convinced Outlook needs some work to fix the problem.
Know Your Options
If all else fails, call your ISP. E-Mail can be a very problematic service to maintain. So, unless you're dealing with a national ISP, who has dozens or hundreds of redundant servers, then it may be continually problematic for you. You can of course, use GMail or HoTMaiL accounts, which are extremely stable and powerful. It depends on whether or not e-mail is mission critical for you. GMail is known for being particularly easy to setup for personal domains. So, if I wanted to, I could setup my own Schvenn.net e-mail addresses to be hosted on GMail's servers. That may not be the direction you wish to go, but it's good to know your options.
Getting The Same E-Mails Over & Over Again
Here's the scenario: you check your e-mail and get five new messages. The server gets to number three and stops, or it takes forever to download the next e-mail, but then fails. So, you check your e-mail again only to see that the first three e-mails download all over again. This happens repeatedly, so that you eventually have several copies of the first few e-mails and the e-mail program never does download those last messages that it indicates are on the server. Frustrating, isn't it?
Typically, this happens only with Dial-Up connections. However, it can happen with high speed connections if you have a lot of packet loss, which is slowing your connection down tremendously, or if the e-mail that your program is getting stuck on is extremely large.
You see, your e-mail program treats downloading e-mail from your account as a single action. It doesn't matter if there are 20 e-mails on the server or 200. So, if the program is only able to download a portion of them, then it considers the whole process a failure. This is because the e-mail program doesn't send the Delete or Mark E-Mails Read commands until after everything has been downloaded.
"Insanity is doing the same thing over and over again and expecting different results." ~ Albert Einstein
What we need to do is figure out what e-mail is causing the problem and eliminate it. Of course, you're not going to be able to do that using the e-mail program. Instead, it's time to log into Webmail. Chances are that the e-mail in question is chronologically next to the last one that downloaded to your computer. It will also likely be the e-mail that has the largest attachment. Most Webmail programs will let you sort results by clicking on the column headers. Click on the column header for Size and look for the e-mail with a large attachment.
On Dial-Up connections, anything over 1MB typically fails when downloading through e-mail. For high speed connections, the file size is probably significantly larger than that, like 15+MB or more. Read that e-mail through the Webmail interface and Move it to a new folder or Delete it. Once you've eliminate the likely culprit(s) from your Inbox, logout and try to get your mail through your e-mail program again. It should work now.
If there are no e-mails with large attachments, then you may simply have a corrupt e-mail. It doesn't mean you or your ISP did anything wrong. Sometimes an e-mail may just get damaged in transmission. Either way, you'll have to use some investigative process to figure out which one is the problem and remove it.
If you're still not having any success, call your ISP.
Getting Every E-Mail Exactly The Same Number Of Times, Usually 2 Or 3
This is an easier fix than you might expect. You probably have a forward setup or a second copy of the e-mail setup in your e-mail client. Let's cover one at a time.
Duplicate E-Mail Account Setup
First, if you use an e-mail program like Outlook or Windows Live Mail, then you might have an e-mail account setup twice, even if it was unintentional. We'll need to check. So, start by opening the e-mail program. Depending on what program you use, you'll need to find the place where the e-mail accounts are configured. Usually, there's a Tools menu and an Accounts/Account Settings option from which to choose.
If asked whether to Add a new e-mail account or View or change existing e-mail accounts, we want to View or change existing e-mail accounts. If there are tabs along the top of E-Mail Accounts/Internet Accounts window that you opened, look for a Mail tab and click that. This is where we'll find all of the e-mail accounts that are setup in this program.
If there is only one e-mail account listed, then this is not the problem, so skip to the next section. Otherwise, we're going to need to check each of the e-mail accounts setup. Usually, you can just double-click an account to open it's Properties window. Once you're in there, the login information is the important part. Just because the e-mail address may say one thing, like moc.erehwemos|bob#moc.erehwemos|bob, doesn't mean that's the actual account it's checking. Depending on the e-mail program, you're looking either for the Servers tab or for the section that has the Username and Password. Whatever Username that is, for example: mary or moc.erehwemos|yram#moc.erehwemos|yram, then you've found the actual account that is being checked. In the example I've just provided, the account looks like it's checking moc.erehwemos|bob#moc.erehwemos|bob, but when we saw the user information, you're really checking Mary's account.
Here's a few examples of how that would look inside an e-mail program:
In Windows Live Mail, the General tab indicates you're checking Bob's account, which was probably what you intended to do. However, when we check the Servers tab, we see that at some point, Mary's Username and Password got entered.


This happens because of user error; usually it's when a Username and Password window popped because the server was having problems that day. Perhaps you weren't paying attention to the account it was asking for and you accidentally changed it to your secondary account. It's a common mistake. Regardless, now that you've found it, you know what to do. Change the Username and Password back to the correct information, Apply the changes and you're done.
Here's a second example of what your account screen might resemble:

Again, you can see that the intended e-mail account is moc.erehwemos|bob#moc.erehwemos|bob, but because the Username is set to moc.erehwemos|yram#moc.erehwemos|yram, then that's the actual e-mail address this account is checking. Adjust the Username and Password to match the proper e-mail address, Save the settings and you're done.
Finally, here's where you would check within Thunderbird. This should cover the majority of the layouts for e-mail programs. There are other variations of course, but between these three examples, finding your specific example should be fairly intuitive.

As you can see for moc.erewhemos|bob#moc.erewhemos|bob's account, the Username information is once again set to moc.erehwemos|yram#moc.erehwemos|yram, which is what needs to be corrected. Match the Usernames and Passwords to the e-mails, Save the settings and you're done.
Between those three examples, you should be able to find the fields best resemble your e-mail program.
E-Mail Forward Setup
This one is going to be tougher to explain, because I can't give you as many visuals to show you what to expect. The first questions is, do you have another e-mail account? If not, then this is not the solution to your problem. You will likely need to call your ISP for assistance, instead.
If you do have more than one e-mail account, then have you ever set it up to receive e-mails from another account? I can't answer that for you. You need to know this answer. Quite often, people will Forward their work e-mails to their personal e-mails while on vacation. Did you do that, at some point? If so, did you remember to turn it off when you got back?
Do you see the line of thought here? If you've setup an e-mail to Forward a copy to another address and you have both of those addresses setup on the same computer, then you will get two copies of that e-mail; one from the original account and one from the Forwarded copy. You will have to check the Forwarding options in each of your e-mail accounts to see if that's the case.
Log Into Your Webmail
If you don't know how to setup a Forward or have never done it, then this is not likely the problem. However, if you have set one up or had your ISP set one up for you, then let's check the settings. For most ISP's you will have Webmail access that's usually located at http://webmail.YourISP.com. In other words, if your e-mail address is moc.erehwemos|bob#moc.erehwemos|bob, then your Webmail site would most likely be located at http://webmail.somewhere.com.
Once in there, you're looking for Settings/Options. Somewhere in there you will find Forwarding options. See if there's anything saved there already and determine whether or not it's going to create duplicate e-mails. If so, remove the Forward and Save the settings. How you specifically do that I cannot tell you. It depends on your Webmail interface, but it should be pretty intuitive. If you need help of course, call your ISP.
For example, Mary is receiving two copies of every e-mail. She checks her work e-mail account settings and sees that she's Forwarding all of her work e-mails to her home account. Her home PC is setup to download both her work and her home e-mail. So, she's inadvertently sent herself two copies of every e-mail. By logging into her work Webmail service she finds this out, because her work Webmail has a Forward setup to send everything to her home address. She erases that setting, Saves the changes and she's done! No more duplicate e-mails.
These images aren't terribly useful, unless you specifically setup a Forward for your HoTMaiL/GMail accounts, but just to give you an idea of what a Forwarding screen would look like, here's a couple examples:
I hope this helps.