On 4/29/21 2:22 AM, Steve Dondley wrote:
Some more nuttiness: I bit the bullet and downloaded a trial version of MS 365 and downloaded the Outlook desktop. On my mac, at least, there are two different interfaces/version of Outlook: the "old" Outlook and a "new," more minimalist version. You can switch between the versions easily.
On the "old" outlook, I was able to get things set up without issue. But with the "new" outlook, I couldn't send email or set up a new account.
I also have seen this. We had a customer within the last month report that the "new Outlook" did not work on port 143 with STARTTLS -- it shows a generic error that it has "a connection problem". I was able to buy a copy of it and duplicate it.
Switching back to "old Outlook" fixes it.
Switching "new Outlook" to port 993 with forced TLS/SSL also solves it. So does disabling STARTTLS on port 143 in "new Outlook".
The "new Outlook" is labeled as a work in progress -- it only received IMAP support at all within the last couple of months! -- so maybe they will fix this.
That said, there's a trend nowadays to avoid STARTTLS due to "STRIPTLS" attacks -- see the "Weaknesses and mitigations" section on <https://en.wikipedia.org/wiki/Opportunistic_TLS>. Port 993 with forced TLS is immune to this.
Because of this, I've changed my company's various email autoconfigure/autodiscover hints and help pages to recommend configuring new clients using port 993 for IMAP and port 465 for SMTP submission (rather than 143 and 587 with STARTTLS). I don't need the hassle of finding out the hard way that new programs are deprecating STARTTLS, if that's what they're doing.
-- Robert L Mathews, Tiger Technologies, http://www.tigertech.net/