With autoconfig do you mean this: https://forum.howtoforge.com/threads/autoconfig-and-autodiscover-for-outlook-2016-2019-etc.83644/ It works for Thunderbird, and I believe also for iPhone email app. Outlook I could not get working with this except for very old version.
yep.. apparently microsoft changed how autoconfig works in exchange/outlook and haven't released any details of those changes publicly. so unless someone manages to reverse engineer what microsoft have done, autoconfig isn't going to work on recent versions of outlook. on older versions of outlook (2010, 2013?) i expect it to stop working once server side support for TLS 1.2 gets dropped. and i'm not sure, and can't be bothered to look it up, but i doubt outlook 2003 supported TLS 1.2, so should already not be able to connect to properly secured mail servers. so looks like outlook configuration is going to remain a manual process for the foreseeable future.
