Re: [Exim] Do Return Receipts Have to be Null Senders?

On Mon, 2004-02-09 at 13:07 -0700, Kevin Reed wrote:
> I happen to be working on a mail problem with an IBM tech and noticed that
> all of his return Receipt messages arrive as regular mail instead of as a
> Null Sender.
>
> I thought this was improper?

It is.

> Perhaps they are doing this because sites are blocking Null Senders??

Perhaps, but only _very_ broken sites do that. It shouldn't be a
consideration, certainly not considered a justification for such
dangerous behaviour.

> I can see a mail loop as a result of this under the right conditions.

Indeed.

> Curious if this is considered acceptable. All of our return receipts go
> out as Null Sender mail.

No, it's not acceptable. If they do this they're (perhaps unwittingly)
attempting to cause a denial of service attack. If I encounter this type
of breakage and it's not fixed after a polite mail (or two) to
postmaster@, I have been known to report it to the abuse contact at the
upstream network provider. These people often take potential denial of
service attacks caused by mail loops somewhat more seriously than their
clueless clients do.


--
dwmw2