Having an over-full inbox can cause a variety of email problems, including slow performance, timeouts, connection problems, and disk quota errors. Follow this article to diagnose and resolve mailbox disk space issues.
Likely cause: You have a very large amount of email stored in your mail account.
Solution: Remove or archive some email. See Reducing Mailbox Size below.
Cause: You have exceeded the disk space either for this specific mail account, or for the domain as a whole.
Solution: You must delete some content from your server/domain/mailbox. Mailboxes are limited and each has a subscription quota.
The ideal size for a mailbox is 50 MB or less. However, many users will be very content with email performance up until about 500 MB or so. At that point, or for accounts with greater than 500 MB of email, you should seriously consider removing or archiving some of the emails. Otherwise, you will notice degraded performance for that mail account.
Many email programs will let you create local folders that are stored on your computer, rather than on the server. You can drag and drop messages from your inbox or Sent folder on the server to your local folder instead. Then, if you ever need to reply to or forward them, just drag them back to your inbox. Note that you should consider having a backup option for your local computer if you do this, because the messages won't be on the server.
The next option will delete all or some of your email, with no regard for individual messages. Pursue these options at your own risk.
Trouble logging in? Simply enter your email address OR username in order to reset your password.
For faster and more reliable delivery, add firstname.lastname@example.org to your trusted senders list in your email software.