OSEC

Neohapsis is currently accepting applications for employment. For more information, please visit our website www.neohapsis.com or email hr@neohapsis.com
 
Re: Sender access restrictions by connecting back to the MX/A server(s)

From: Wietse Venema (wietseporcupine.org)
Date: Wed Oct 01 2003 - 19:16:41 CDT

Guido Van De Velde:
> For instance a mail from userhost where host does exist and has regular
> dns A and PTR records, but its tcp/25 is protected by our firewall. I
> know it should be userdomain with mx'es reacheable from Internet, but
> is it up to someone else to judge on that ?

This means that delivery problems cannot be reported back to the
sender, because their address is invalid. The mail simply disappears
down a black hole. This is generally undesirable.

> They refer to
> http://sourceforge.net/docman/display_doc.php?docid=6747&group_id=1
>
> Is this behaviour normal ? We do everything to keep out virussen and to
> check on spam. We are _not_ open-relay. We only send out regular mail.
>
> Has anyone an opinion about this ?

No-one is required to accept mail with an invalid sender address.

        Wietse