[prev in list] [next in list] [prev in thread] [next in thread] 

List:       postfix-users
Subject:    [pfx] Re: Behaviour in case of multiple relay hosts with multiple DNS records
From:       Viktor Dukhovni via Postfix-users <postfix-users () postfix ! org>
Date:       2023-12-29 18:59:42
Message-ID: ZY8XHpU9vJgjscRz () straasha ! imrryr ! org
[Download RAW message or body]

On Fri, Dec 29, 2023 at 07:45:45PM +0100, Peter Wienemann via Postfix-users wrote:

> > And then shows some examples that deminstarte that the using
> > MX records is mutually exclusive with using address (A or AAAA) records.
> 
> I think what bears the potential for confusion is what you mean by "trying
> MX records". In my opinion the example showed that MX lookups are always
> tried, even if MX records are not present

That's of course unavoidable to determine *whether* they are present.

> In that sense MX and A/AAAA (DNS) trials are not mutually exclusive.

> What is mutually exclusive is the subsequent delivery attempt. Either
> destinations specified by MX records are tried if there are any or
> otherwise delivery is attempted to hosts specified by A/AAAA records.

As already noted, delivery is mutually exclusive, to either the IP
addresses of hosts found in MX records, or to the addresses of the
domain if MX lookups return NODATA.

RFCs 5321, 2821 and 821 have been around long enough to expect
compliance with core elements of the SMTP specification from any
mainstream MTA, and particularly Postfix, which appears to be the most
widely deployed MTA by some measures.

-- 
    Viktor.
_______________________________________________
Postfix-users mailing list -- postfix-users@postfix.org
To unsubscribe send an email to postfix-users-leave@postfix.org
[prev in list] [next in list] [prev in thread] [next in thread]