It's not on any blacklists according to mx toolbox (
https://mxtoolbox.com/SuperTool.aspx?action=blacklist:vansairforce.com&run=toolpage)
The problem is going to be with the lack of MX and SPF records and DKIM/DMARC signatures. White lists don't really exist much anymore beyond the system MS uses (I can't recall its name off the top of my head but last I checked it costs thousands/year to join).
The emails that a forum send naturally trip the spam/phishing filters since they have phrases like "account", "log in", "unread message", etc. And without the SPF/DKIM data it's going to get effectively g-lined.
