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.
Mails that have been sent to you in error can be forwarded in Thunderbird to the correct recipient of the email. This is happening regularly in companies for example where emails may reach the wrong recipient.
The forwarded message however does not look like the original one because it normally has the mail header attached to it. This looks pretty ugly and is not needed most of the time.
The Thunderbird add-on Mail Redirect allows you to redirect mails instead of forwarding them. The core difference is that a redirect sends the original mail along its way, while a forwarded mail adds the header information to it.
This ensures that the recipient will only see the original message and not the information that are attached when the email gets forwarded.
he extension Mail Redirect adds a Redirect option to the Thunderbird right-click menu which means that you can redirect multiple emails at the same time.
Instead of making use of the right-click menu, you can also use the keyboard shortcut Ctrl-B to do the same.
Emails that you want to redirect (or bounce) are opened in the following way in Thunderbird.
The resend mail form looks slightly different from regular mail forms. The first difference is the resend from menu at the top. Select one of your email addresses which you want used to resend the email.
You then need to add another email address under resend to, which is the target email address you want to send the email to.
The third and final difference is that you cannot add text or other data to the email, it just contains the same data that it arrived with.
The extension offers a couple of settings that you can take a look at when you open its options page in the Thunderbird add-ons manager.
Here you can disable the option that stores a copy of redirected mails in the sent folder, or add default to, cc and bcc resend recipients to make things easier.
This can be useful if you redirect messages to the same recipient at all times, or include a recipient at all times when that happens.