How to stop duplicate emails.
Downloading Old Inbox
If your entire inbox of old emails is being downloaded again, you are most likely using a POP type email account where you leave a copy of each message on the server. Sometimes the network connection between your computer and the server gets reset, and this will unfortunately make your email client behave as if it is connecting to a "new" mail server, so it tries to download all of the emails again.
There are a few ways to prevent this from happening. You can switch to using an IMAP account instead of POP, and then your computer and the server will stay in sync. Or, you can check for a feature in your POP email client that allows you to automatically delete messages from the server after a certain period of time - this is usually an advanced setting. Finally, you can manually log into your webmail once a month and delete or archive old messages from the server.
Single Repeat Email
There are a couple of ways that you might receive a single email over and over again.
- There might be a "hiccup" between the mail servers, which should result in only one or two extra copies.
- The sender of the message may be experiencing a failure with their email client. In particular, antivirus software can interfere with Outlook's ability to recognize that it has sent a message, prompting it to send the message over again. Try having the sender disable their antivirus software temporarily.
- There may be a forwarding or auto-responding loop set up between different email accounts. Check for any forwarders that are set up to or from any of the affected accounts. Also, check for any autoresponders on the affected accounts.
In the case of duplicate emails, it may be helpful to learn whether the email was really sent twice - in which case the problem is on the sending side - or whether it was duplicated on the recipient side. Checking the timestamp on the message can help determine this - emails that are sent multiple times will have different timestamps, while true duplicates will have the same timestamp.
To check this, view the email headers for two of the duplicate messages. The help documentation for your email client will show you how to find the header. In the last Received line, look for the timestamp. It will be different if the message was sent more than once, while it will be the same if the hiccup occurred further down the line.