On 2020-09-30 Allen Coates wrote: > On 30/09/2020 15:58, @lbutlr wrote: >> On 29 Sep 2020, at 11:46, J David <j.david.li...@gmail.com> wrote: >>> domains that have no email service, i.e., those domains have A >>> records in that range but no MX records at all. > > Question at a tangent:- > > Does the SMTP daemon resolve a destination if there is no MX record?
Normally Postfix will check for an MX first, and if that is absent check for an A record for the domain. This is standard MTA behavior as defined in section 5 of RFC 5321. <https://tools.ietf.org/html/rfc5321#section-5.1> If a domain should never receive mail it's better to define a null MX for that domain (see RFC 7505). <https://tools.ietf.org/html/rfc7505> Regards Ansgar Wiechers -- "Abstractions save us time working, but they don't save us time learning." --Joel Spolsky
