Author: Sheldon Hearn Date: To: Alan J. Flavell CC: Exim Users Mailing List Subject: Re: [Exim] OT: Problem sending mail to verizon.net
On (2003/11/06 00:04), Alan J. Flavell wrote:
> > There's no real point to doing any "active/real-time" sender address
> > verification by way of SMTP connections to the sender's MX, and worse
> > ends up causing all these problems you're complaining about.
>
> It's a point of view; but if done *selectively*, our experience is
> that it can keep out a deal of spam, so I wouldn't reject it out of
> hand.
>
> OTOH, if done *globally* it would doubtless result in some loss of
> bona fide mails (from misguided MTAs, maybe, but the users were bona
> fide);
Concrete example of an MTA that you'd lose mail from, which can't be
described as misguided: MTA on a dynamic IP address using dynamic DNS
with a short TTL in the zone and ETRN to force the queue from a backup
MX.