If you connect to Outlook via a Mac email client and your organization requires a fresh login after a certain number of days set by its security policy, you might find yourself mysteriously stymied and be unable to troubleshoot the problem if you hit the same snag I did recently.
After years of receiving weekly requests to perform a login and two-factor authentication via my browser for an Outlook account, it suddenly failed. No amount of troubleshooting seemed to allow me to reconnect. Strangely, on a different Mac, authentication continued to work without a hitch.
After a substantial amount of trial and error, I discovered a new piece of software that I had installed interfered with my email client’s browser launch. The new software, PeakHour, operates a tiny local web server to manage some information gathering about your Mac’s data usage. As with all internet-based servers, it requires a port number–a unique number that identifies a particular service on any internet-connected device, like email, secure web browser, and the like.
In trying to troubleshoot an unrelated network problem, I had installed PeakHour, which enabled its server at port 8000. What I didn’t realize (and you can’t find documented anywhere) is that either Outlook or some email client use port 8000 to create a short-lived local web server to manage the authentication with Microsoft’s Outlook login systems. Because my email client couldn’t launch a web page at port 8000–the PeakHour page came up instead–it failed to authenticate.
Most software that creates a local web server also has the option to change the number. I changed it from 8000 to 8002, restarted PeakHour, and was immediately able to get my Outlook email account working again. Check the settings for the software for such an option.
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