See if your Firewall is blocking Thunderbird. The 'Firewall' may be part of your Anti-Virus product. Thunderbird must be an allowed program otherwise the Firewall will block access to internet and Thunderbird will not be able to contact/connect with servers etc.

Also suggest you stop Anti-virus product from scanning Thunderbird folders on startup and stop scanning incoming emails.

What Anti-Virus product are you using ? Does the Firewall have Thunderbird set up as an allowed program?

Perform some tests if above does not work.

• Start Thunderbird in 'Safe Mode'.

Info: https://support.mozilla.org/en-US/kb/safe-mode-thunderbird?redirectlocale=en-US&redirectslug=safe-mode#w_how-to-start-thunderbird-in-safe-mode

If still not working:

• Restart your Computer in 'Safe mode with networking'.
• Start Thunderbird.

Please report back on results.

It appears that my inbox was corrupt. I'm not sure what caused this but this has happened a few times. I need to figure out what is causing it or switch to a different email platform.

re: Inbox being corrupt.

I would start with Anti-Virus. If it is scanning folders on startup or emails on download then it could be causing you issues. This is a common problem with AV products and Email Clients.

• http://kb.mozillazine.org/Email_scanning_-_pros_and_cons

Advise the Inbox is used for new incoming mail and mail that needs sorting, but it should not be used as a general storage file. So, keep the numbers low.

Emails are not stored as separate files, they are written to one mbox text file one after the other in the order downloaded. This file gets the most activity as new mails are added to the mbox file, emails get moved, deleted are marked as deleted etc. Old marked as deleted emails are only removed when you compact, so if you delete several emails each day, I would advise you compact the Inbox at the end of each day. The Junk folder should also be compacted after emptying.

A lack of regular maintainance such as compacting can cause files to become corrupted over time.

Imap Inbox can be purged/compacted automatically upon exit. This is set up in the imap 'Account Settings' > 'Server Settings'.

Auto compacting can also be setup to request running when it will save you x amount. I recommend you do not set the X amount to more than 10MB and ideally a lot less. This is set up in 'Menu icon' > 'Options' > Advanced' > 'Network & Disc Space' tab.

Info on keep it working:

• http://kb.mozillazine.org/Keep_it_working_%28Thunderbird%29