Did your ability to receive mail suddenly stop?

• Check the service status of your ISP. (Many ISPs have a status or alert page on their website.) They may be having technical difficulties.

• If your ISP provides a web-based email interface, try to log in and view your mail. If you can see your messages, the problem is probably related to your account configuration.

• If you cannot log in to your ISPs web-based email interface, your password may have changed. If so, it must also be changed in Thunderbird. To change your password:
  • At the top of the Thunderbird window, click the Tools menu and select Options, or click the menu button  and choose Options.
  • On the Security panel, click on the Passwords tab and then click Saved Passwords….
  • Click on the relevant account and then click Remove.
  • Close and re-open Thunderbird. You will be prompted to enter a new password for the account.
• If you recently updated Thunderbird, the firewall component of your Internet security suite may have blocked access of the new version of Thunderbird to the Internet. When this happens, IMAP folders may also disappear. There is some basic information about antivirus products and their known bad interactions with Thunderbird.Remove Thunderbird from your firewall’s list of trusted or recognized programs, then add it back manually (or when prompted). Otherwise, consult the documentation for your security suite / firewall / antivirus product for instructions on how to modify the firewall component of that product.