Re: [Exim] SMTP Sender-verify callouts

On Mon, 16 Aug 2004, warren, anthony wrote:

> I have recently tried using SMTP callout's to verify senders
> validity. For the most part it is working fine, however I am having
> difficulty with some senders that I know are valid.

That comes as no surprise.

There are some around here who say that verifying senders by callout
is plain wrong, and I can appreciate their point...

But from a practical point of view, I have reported that selective
application of the technique can be beneficial. You certainly can't
just turn it on globally and expect to get good results, that's for
sure.

> When Exim performs a callout does it call back to the sending
> server's apparent DNS name or does it connect to the source IP
> address?

No; it calls the MTA which is appropriate to the domain in the
(purported) envelope sender address.

This has nothing necessarily to do with the server which is actually
offering you the mail.

But if you want to go into specifics, I fear you'll need to show some
actual addresses. If this violates your privacy rules then fair
enough, but discussion is inevitably going to be less productive.

good luck