For Pobox Basic and Pobox Plus customers, check to make sure you aren't forwarding your mail to more than one place. If you are only forwarding mail to one destination, contact Customer Support for more assistance.
For Mailstore customers, start by checking webmail. If multiple copies of every message are appearing in your webmail, please contact Customer Support immediately.
If you only have one copy of each message in webmail, but more than one copy in your email program, there are a couple of things that could be happening:
1. You're forwarding your mail to another address, and that address is also set up to read mail in your email program. If this is the case, you should probably remove one the other address from your email program, or stop forwarding your Pobox mail to that other address.
2. You accidentally set your email program up to check your Pobox account twice. If this is the case, you should be able to "delete" one account (which is actually just the same account a second time), and the second copy of all the messages will disappear
3. Your email program is somehow duplicating the messages when it downloads them. This should only happen with very, very old email programs, and the best solution is generally to upgrade to a more modern email program. Thunderbird is a free program that is very, very good, so it's a good alternative if cost is a factor in upgrading your email program.
If none of these cases describe your situation, contact Customer Support for more assistance.