Guess we have to use gmail then. I tested 3 "Microsoft" emails. Hotmail.com and .fi and outlook.com. Anyhow the mailserver/domain seems to be on somekind of public blacklist, or there is dns issues, since it gets rejected by private servers also(rspamd).

I don't know if this is the right place to put this, but there seems to be something wrong on faf email server. I have been trying to register an account and the registration email get's hammered by the spam filters so hard, it doesn't even appear on spam email folder. Tried to send it to private mail server, where the mail gets also rejected.
Spam filter report for the registration email(on the private server). Positive values are bad:
HFILTER_HOSTNAME_UNKNOWN (8.5)
MX_MISSING (3.5) []
FORGED_W_BAD_POLICY (3)
MX_INVALID (0.5) []
MID_RHS_NOT_FQDN (0.5)
R_DKIM_ALLOW (-0.2) [faforever.com:s=postal-FCXQyW]
MIME_HTML_ONLY (0.2)