Haha!
> next monthly meeting IN PERSON, on Tuesday, April 2nd, at 7:30pm. Yes, that's the FIRST Tuesday of the month
That April 2nd was the FIRST Tuesday of LAST month! So, your SPF and DKIM aren't aligned properly to pass DMARC. :)
By the way, for the meeting, don't forget the new (upcoming) kid on the block, BIMI, that will also increase in relevance to the topic at hand.
Hartmut