Re: [exim] Exim domain and login checks for relay

Alan J. Flavell wrote:
> On Sun, 16 Apr 2006, Jeremy Harris wrote:
>
> [...]
>
>>- reject senders not matching the specific auth data
>
>
> "Rejection" is not as easy as it sounds. We try to reject mail
> submissions which present non-existent sender addresses - but mail
> client software typically does not react well to a 5xx telling it that
> the client's purportd sender address is invalid. We've seen quite a
> number of different scenarios in which the client station then
> continues to batter the mail server with repeated attempts to send the
> mail, more or less indefinitely until the mail admin steps in.

So? Ratelimit'em too. One too many, and into the firewall they go.
It's one way to get then edjicated :-)

- Jeremy (the barbarian)