Domainless SMTP and alternative port 2525 #5
Description
The SMTP and all this SPF and other crap is focused on a domain. For a self hosting and direct mailing this all is not needed. Also the 25 port is often just blocked on ISP level. We should make all SMTP server to simply fallback to 2525 port to bypass this firewalls.
Similarly to SSLH we can use one port for all mail needs: both SMTP and POP, TLS etc.