There are a few of situations which may cause Outlook to download duplicate messages:
- Outlook Downloads Messages from a POP3 Server Twice http://support.microsoft.com/default.aspx?scid=kb;en-us;292249
- Mail Retrieval Problems Occur When You Receive POP Mail http://support.microsoft.com/default.aspx?scid=kb;en-us;317945
- Password Prompt, Duplicate Messages Appear If Outlook Profile Has Two POP3 Accounts http://support.microsoft.com/default.aspx?scid=kb;en-us;284404&Product=ol2002
- POP3 Headers Are Duplicated http://support.microsoft.com/default.aspx?scid=kb;en-us;289942&Product=ol2002
- You are Using Anti-Virus Software Many anti-virus programs can cause this issue as well. If the message is large, the software causes a 'timeout'. As a result you recieve the message over and over.
How can I stop this situation?
The easiest and fastest solution to this problem is to log-in to the mail server and delete your mail message that is causing the problem - or all of them for a fresh start. (NOTE: make sure that you have downloaded your messages first)
Other things to prevent duplicate emails
- Increase your server timeout settings to 10 minutes:
- Configure Outlook so as not to check e-mail more frequently than ten minutes.
- Configure Outlook to download complete Item including attachments.
- Tools|Send/Receive settings
- Define Send/Receive groups.
- Click to select the group name, and then click Edit.
- Under Accounts, click to select the POP3 account.
- Download complete Item including attachments.
Outlook Server Timeouts
If you have trouble sending or receiving mail in Outlook, or if your Outlook installation is sending duplicate emails, it can help to increase the Server Timeouts setting in Outlook. To this, perform the following steps
- In Outlook, open the settings for the account (by clicking Tools then Email Accounts)
- Once you've opened the settings for your email account, click the More Settings button
- In the More Settings pop-up window click the Advanced tab. Increase the Server Timeouts value to 5+ minutes
- Click the "OK" button then click "Next" to close the account settings window
At this point, it is recommended to restart your computer to force-through this adjustment to your Outlook settings.
Outlook Express Error 0x800CCC0F
Symptom: When opening Outlook Express or sending/receiving e-mail, you receive the following error message:
Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity. Account: 'mail.yourdomain.abc, Server: 'mail.yourdomain.abc', Protocol: POP3, Port: 110, Secure(SSL): No, Error Number: 0x800CCC0F
Solution: This error is most likely related to AntiVirus software such as Symantec. Follow the steps provided in the WORKAROUND to resolve the issue. http://support.microsoft.com/default.aspx?scid=kb;en-us;813514
Outlook is unable to connect to your incoming (POP3) e-mail server pop3
Restarting your computer will generally correct this error.
If that does not solve the problem, you should contact the support department via support ticket and include the email address, the complete error message you are receiving, and the POP3 server you are using.
Automatic Compression/Zipping of Attachments
- Symptoms: Whenever an email is sent from Outlook with attachments, those attachments are compressed and placed in a zip folder.
- Solution: If this is unreplicable in Webmail, then it's most likely due to a program called WinZip being installed on your machine there. (not a malicious program)
- Turning Zip Attachments off by default:
- Click Start and click All Programs
- Scroll down to and click WinZip Courier
- Click Configure WinZip Courier
- Note: With Windows 8, you can just click the Configure WinZip Courier tile on the Start page
- Click the Attachment Options button
- In the top of Attachment Options click in the check box next to "Zip files..." in order to uncheck the box
- Click OK and then click Close