On Wed, Jul 05, 2017 at 06:57:17PM +0200, Stefan Sticht wrote: > is there a RFC or similar which suggests/requires that the helo > name should be DNS resolvable?
I think you are looking for RFC 5321: https://tools.ietf.org/html/rfc5321#section-2.3.5 See also section 4.1.4 as linked from there, and also 4.1.1.1 which explicitly lays out the EHLO/HELO syntax. -- http://rob0.nodns4.us/ Offlist GMX mail is seen only if "/dev/rob0" is in the Subject:
