Logs of that Goofy Outlook software
Thanks for the tip: very precious functionnality I wasn't aware of.
I think Outlook was afraid of your surgical skills, as in ability to dissect its inner workings: as soon as I set up the logs, closed Outlook and reopened it, the IMAP - SMTP just started working again!! Good gracious... Tested again: works all the time.
If ever it starts acting up on me again (and it will), I'll post relevant logs. It just might do the trick again.
SSL, TLS and ports 25, 465, 587
Outlook started acting up again with the same symptoms this very morning, but I think I found a few clues about the problem.
I should have stated yesterday (my mistake) that I configured Postfix to listen on submission port 587, to get around ISPs that preclude the use of port 25, wanting to set up SMTP to be reachable anywhere and everywhere without changes in the client settings at each new location (hotspots, hotels, etc.).
Thunderbird handles very well TLS AUTH on any port you ask him to connect to. Outlook, the fickle software from a company you might have heard of, doesn't handle TLS very well on other ports than 25 (I'm not even sure it can do that reliably). From my experience now, and from multiple postings on the usenet and the web at large, I can see I'm not the only one to have encountered the problem.
Two questions to any experts out there:
a) I would certainly like to set up Zimbra to handle SSL or TLS transactions on other ports than 25. Would it be advisable to setup Postfix to handle port 465 (SSL) for Outlook, and 587 (TLS) for other more reliable clients?
b) Can I set up SSL on 465 with Zimbra (I would settle on that single port if it's possible)? I see in the admin console that there is a checkbox "TLS only". Does that mean that if I uncheck it SSL might be available, or does it just turn off all types of encryption?