Re: Frank Carmickle and Marco Paganini must die

[Blu <blu@daga.cl>]

On Thu, Sep 23, 2004 at 08:42:07PM -0700, Richard A Nelson wrote:
> On Thu, 23 Sep 2004, Adam McKenna wrote:
> 
> > On Thu, Sep 23, 2004 at 07:38:59PM -0400, Blu wrote:
> > > Scenario 3:
> > >
> > > -    User emails me about something
> > > -    My MTA, before accepting the message, calls back to the user's mx
> > >      and stablishes an SMTP dialog to check if the user is able to
> > >      receive mail from me (with envelope <> to avoid loops).
> 
> Which MX ? does it try them all, followed by the A record ?

First, this is not my invention, it is an Exim feature.

Now, answering your question, yes, it tries all hosts until one of them
issues a 5xx response in which case the verification fails, or one of
them issues a 2xx response, in which case the message is accepted.

> 
> > > -    As the user's MX rejects any message from me, the original message
> > >      from the user is rejected with a 550 saying something like "Your
> > >      host is rejecting mail from us. This host will not accept mail that
> > >      cannot be answered"
> 
> What about temp failures ? Do you generate 4xx in that case ?

It is configurable. You can issue a 4xx or simply accept. Issuing a 4xx
gets rid of lot of spam though.

Blu.