What are the exact error message(s)?
+No error messages - just no connection. Just says not able to connect. With Thunderbird, it the error log on the client says the server doesn't support TLS. The server's SMTP log says "fatal, too many errors, program terminated"+
How is the local network configured?
+Can you be more specific?+
Are you even able to connect to the mail server via telnet?
+I don't use telnet - don't even know what it is.+
If you're getting to the mail server, can you connect to port 25? (eg: using telnet to connect to port 25)
+Yes, I can connect to port 25 with the clients if I drop to PLAIN. I know this because the Outlook client says it's connected but the authentication won't occur - it just keeps asking for the password over and over. I think is particularly odd in the case where I've dropped to PLAIN+
If you can connect into port 25 via telnet, is it responding like a mail server?
+No responses+
If you've connected to port 25 and it's a mail server, what (other) ports are you connecting to?
+Not sure what you're asking. With another service?+
Are you using authenticated connections for sending? Port 587, etc.
+As I already indicated, those don't work.+
If you're connecting, what sort of relevant "stuff" might be present in the mail server logs after a failure?
+See the log messages I mentioned above.+
Can you connect from that Windows 7 box and clients to another IMAP or POP3 server elsewhere?
+Don't know - don't have one.+
I'd also encourage you to pursue this with the Microsoft Windows and Microsoft office forums and folks; Windows is the most central part of this, and you're here connecting to a standard IMAP or POP3 server. Which means this is primarily with the client platform, and secondarily with the server. You could, for instance, be connecting that Windows box to most any platform.
+I'll certainly follow up with their forums. This seems, however, like it might be a pretty common problem and it's certainly relevant for this forum. Maybe someone else on the forum could help? Thanks.+