Comment 9 for bug 1721803

Google and others require SPF/DKIM and all the modern shebang before they even start looking at incoming mail. Does the domain have all that? Also, there is IP reputation to keep in mind and since this server has come on and off RBLs, the reputation may be low.

The easiest solution is to hook this up to a mail delivering service like Mailgun and similar. Otherwise, maybe consider using mail.openstack.org which has higher reputation? The drawback is that people may start marking mail from ask.openstack.org as spam (instead of changing their preferences) and take mail.o.o's reputation down. Tradeoffs :(