Re: [Exim] Reaction to rude 554 greeting

"Greg A. Woods" <woods@???> writes:

>> Some people use the 554 greeting to indicate "no mail under this
>> domain", some to say "please try the next MX".
>
> Those who think the latter have not properly interpreted the RFCs.

This may be the case, but their practical experience shows them that
it works, most of the time.

On my own MTAs, I won't play by their rules, and have no problem with
the current Exim behavior. At work, I'd really like to maximize
likelihood of mail delivery, by mimicking the behavior of other MTAs.

> Any 5xx response is always a _permanent_ failure, even if it is given
> instead of a 220 greeting response.

Permanent failure for that host, yes. But it's a bit hard to tell if
it applies to the message which is being delivered. After all, the
receiving MTA has never seen the message.

> A 5xx response to a connection attempt simply means fail the current
> delivery attempt (i.e. bounce just the one message from the queue).
> Nothing more, and certainly nothing less. Do not pass go, do not
> collect $200, and definitely do not go on to any other MX host!

Again, the problem is that people use the 554 opening message
successfully, with a different meaning.