Investigate SPF "Soft fail"
I got one of the emails from the civicrm.org
security announcements. In Gmail, there's an option "Show original" which has an interesting report. The message makes it to my inbox (perhaps because of the history; perhaps because of the DKIM), but it shows a failure about SPF.
@bgm I'm not sure how we're routing mail right now. Perhaps we need some DNS tweak?