Renewing sendmail.pem, and other self-signed certs

[Gordon Messmer]

Thanks, Philip.  I was guessing that the sever was having some trouble 
completing the TLS handshake, but that looks fine.  You said in your 
original post that Thunderbird balks, but described only the server's 
behavior.  What, exactly, does Thunderbird do when you try to connect? 
Have you tried removing the old certificate from Thunderbird's database? 
  Try that: Edit->Preferences->Advanced->Certificates->View 
Certificates->Servers.  Locate the entry for your cert and remove that one.