A bad day at the office is if you’re entire email system goes down, apparently due to a firewall issue.
This article documents with screenshots how all modern email systems for an ISP requires authentication, and where to look for these illusive settings. Old version of Outlook didn’t bother with this setting, so if you’re using ancient software you’ll experience this problem more frequently. Mac Mail doesn’t support autoconfig, so every time your user has some kind of problem you would need to go and check if the Mac operating system hasn’t erased the authentication setting.
Without further adieu, here are the screenshots in question:
Help! Please Set Authentication to Password! Do not Automatically Manage!
Help! I’m using such an old version of Outlook! I’m a support intensive user, please answer my calls!
As you can read from my tone, I only give you the basics here so that you can do the rest.
But the people who inspired me on this round was definitely Blue Host, which has created a really gorgeous article with probably all the authentication settings that you would ever want. Follow this link: https://www.bluehost.com/help/article/email-client-enable-smtp-authentication