[Mimedefang] sending relay has no MX record?
David F. Skoll
dfs at roaringpenguin.com
Mon Jan 31 12:09:39 EST 2005
On Mon, 31 Jan 2005, Adam Lanier wrote:
> Technically, a server can generate mail (legally according to RFC's)
> without having an MX record. Only servers that RECEIVE mail need to
> have an MX record.
They don't need to have an MX record; an A record will do.
roaringpenguin.com, for example, has an A record. If roaringpenguin.com
had no MX records, then mail for foo at roaringpenguin.com would go to the
A record.
> What needs to be in place is a valid return path for the mail that is
> generated. So, while server 'mailout.example.com' can generate mail
> from the domain 'example.com' with only an A record, some server
> somewhere SHOULD (again, according to RFC's) have an MX record for the
> domain 'example.com'. If there is no MX record for the domain
> 'example.com' then the 'mailout.example.com' will be used as the return
> path for the generated mail.
No; if there's no MX record for "example.com", then the A record for
"example.com" will be used, if it exists. If no A record exists either,
then it will be impossible to mail anyone at example.com
--
David.
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