RE: [AMaViS-user] FINAL DECISION: Will our machine handle it

[Bojan Z. <Bojan.Zdrnja@LSS.hr>]

 

> -----Original Message-----
> From: ama...@li... 
> [mailto:ama...@li...] On Behalf Of Gary V
> Sent: Tuesday, 26 July 2005 4:05 a.m.
> To: Stuart Johnston
> Cc: ama...@li...
> Subject: Re: [AMaViS-user] FINAL DECISION: Will our machine handle it
> 
> I've read that Exchange 2003:
> "Exchange can now be set up to refuse messages for nonexistent users,
> and you can choose not to send a non-delivery receipt (NDR) when a
> message arrives for a nonexistent user. This prevents the common
> dictionary attack where a spammer tries to determine which e-mail
> addresses are valid in your domain by sending test e-mails to
> thousands of names and watching for NDRs.
> 
> So it looks like Redmond is shifting its philosophy, but like I said,
> IMHO not sending reject notices (at least for nonexistent 
> users) is dangerous.

Exactly! In my opinion, silently discarding e-mails for non existent users
is even worse then sending bounces.
Why is that? Because the end user can't expect reliable e-mail delivery
anymore. He can't be sure that he didn't mistype recipient's e-mail address
anymore - this "solution" won't send a NDN and the sender won't know that
his message wasn't received by the recipient.

Therefore (as it can be already seen :), I'm strongly for rejecting non
existent users at the front end. Yes, there are some negative sides about
this (makes it easier to harvest working e-mail addresses), but I think that
the benefit of not deailing with bouncers greatly overweights this.

Cheers,

Bojan