Try doing a test run in safe mode and see if it works.

MMPStudios said

good day, I did a mozilla update of some sort last night and for some reason, thunderbird wont deliver emails from 2 of my accounts that are located on the same server. it just tells me it is connected to that server but never delivers anything from it. this was working fine until this recent update that was performed. Any assistance is appreciated.

I received ths error message: Timestamp: 7/18/2015 7:50:34 AM Error: An error occurred during a connection to mail.mustangmermaid.com:110.

SSL received a weak ephemeral Diffie-Hellman key in Server Key Exchange handshake message.

(Error code: ssl_error_weak_server_ephemeral_dh_key)

The error means your email provider's server is not properly configured and exposes you to the LogJam attack. Thunderbird is trying to prevent that. https://weakdh.org/

As a workaround you can install this add-on. https://addons.mozilla.org/en-US/firefox/addon/disable-dhe/

Note, this will allow you to connect to the server in a secure way, but it doesn't address the underlying problem of the server still being vulnerable.

Check this article if you are having difficulties installing the add-on for Thunderbird. http://xenos-email-notes.simplesite.com/416814616

You should also contact your mail server administrator and let them know you have the error so that they can address the issue on their end. There are a lot of 'fixes' for these browser related errors but I haven't seen too many for TB. But regardless of the fix, as christ1 pointed out, your server is still vulnerable and this needs to be addressed for your own peace of mind. Call them and let us know how it goes.

Thanks. I will try the work around. I am at a university and will let them know about this, but I am not sure how responsive they will be. Thanks for the help.