I am using the Jessie/Symbiosis system
I have recently encountered a complete block using SMTP on secure port 465. I am getting "operation timed out waiting for response" when using Outlook
I can also send mail okay using Roundcube and receive mail fine using Outlook
There are no errors are report in /var/logs/mail.log. I get the usual handshake when POP3.
A quick check using nc on the host, and openssl from a windows dlient, show that the port responds correctly and is open for negotiation. I haven't attempted an AUTH command in either session.
I have noticed lots of "disallowed plaintext auth" in my mail.log over a handful of dates. Is it possible that Symbiosis has locked-down?