Re: [Exim] Reaction to rude 554 greeting

"Suresh Ramasubramanian" <mallet@???> writes:

>> Exactly this is the idea. It could try another MX, to increase the
>> likelyhood of mail delivery.
>
> 5xx means "go away".

For this host. I'm not sure if it means "stop delivering mail to this
domain forever". Quite a few people think it doesn't.

> Trying to go through the backup MX when you get blocked at the
> primary,

The message is not blocked, the receiving SMTP agent, doesn't even
know the message, so this case differs from the usual ones.

> If, for example, I was blocking your IP in some way, and you tried to
> get around my block by trying to deliver through a backup MX, your IP
> would go straight into our firewall deny rules.

Hmm, would you mind looking up the way SMTP is supposed to work? MTAs
are expected to work this way. If no IP connection can be made to the
first MX, other MXes should be tried. As a result, SMTP mail delivery
is extremely robust, and certainly you don't want to change this.