Security exception

User Help for Mozilla Thunderbird
Posts: 125
Joined: June 17th, 2005, 8:45 pm

Post Posted April 13th, 2019, 8:46 am

I keep getting this message on one of my accounts: and do not have a clue what it means and/or what to do about it, if anything. I will appreciate any and all advice.

Thanks to those who know more than me,
Joe Dempsey
Ol' boy from LA (Lower Arkansas)


User avatar
Posts: 45481
Joined: July 30th, 2003, 5:06 pm

Post Posted April 13th, 2019, 9:02 am

It means there is something wrong with the SSL certificate the POP server provides. The certificate is needed to help authenticate who you are really connecting to, and to encrypt the secure connection. You need to use the view certificate button to figure out whats wrong with the certificate. It might be for the wrong host, out of date etc. Administrators for mail servers occasionally make mistakes like that. Your main risk is somebody getting a copy of your username/password if they are trying to masquerade as your POP server. See

If you are sure you are really connecting to the right POP server you can tell Thunderbird to make a security exception (i.e. ignore the warning). However I suggest you duplicate the error using a browser to log into their webmail (so that you can pushback on an attempt to blame it on Thunderbird) and then call your email provider. Hopefully they will confirm its a known problem that they will fix in a few days.

Posts: 361
Joined: January 30th, 2019, 9:38 am

Post Posted April 13th, 2019, 9:10 am

As a website, https connections to work fine. The certificate for the pop3 server is probably misconfigured. It likely points to www.joedempseyphoto or joedempseyphoto, therefore the "belongs to a different site" error. It should point to pop3, or to a wildcard certificate, * If you are the only person who needs to access that email server, you can store the wrong certificate permanently and there should be no side effects and the message should not keep occurring. However it may be a sign that your certificates in general are misconfigured. That would mean that any non-https connections could also give errors. So, if you have an ftp site, its ssl certificate may be pointing to www as well, so anyone logging in to it would get an error.

You also should send some test emails and verify that they go through are not caught as spam by some popular email services, to make sure there are not other problems with how the mail server is set up.


User avatar
Posts: 16755
Joined: November 18th, 2002, 6:44 pm
Location: Somewhere in SE USA

Post Posted April 13th, 2019, 9:12 am

One other possible cause is that your computer system's date/time/timezone settings are incorrect thus making the server's SSL certificate date appear to be invalid.
Doug Wilson, "The Makai Guy"
Win10 (64bit): FF Quantum 68.0 (64bit), TB 60.8.0 (32-bit) ║ Android 8.0/7.1.1: FF Mobile 67.0.3
No TB for Android available, dammit!
What a fool believes he sees, no wise man has the power to reason away - Doobie Brothers

Return to Thunderbird Support

Who is online

Users browsing this forum: No registered users and 3 guests