Let me say up front I'm a 40+ year computer professional, so when I ask for help it's generally a pretty good question.
My main platform is a Windows 11 Pro laptop (all updates) and I use MS Office 2021 Outlook for my email. I use a POP server, not imap. I NEVER get emails from the OGR forum on that platform when there's an update to one of my posts. The other day I looked at my SPAM email folder on my iPhone (I use standard Apple mail using the imap server), and there was email from OGR. I moved it to my inbox on my iPhone, and then it also appeared on Outlook.
My email domain is att.net, and I suspect they mark it in some way so that MS Outlook doesn't even consider it and refuses to download it to my PC. However, Apple mail thinks it's simply junk so I can go through it on the junk folder there. As you may know, even though I move it to the inbox on the iPhone, Apple will always consider it to be junk.
Have your IT people heard about this? I've looked into att.net email settings (they say they aren't the problem) as well as MS Outlook, and can't find a solution.