[TriLUG] AOL's new email policy

[Joseph Tate]

Sendmail can do this, and I've set mine up to do so.  If the domain of 
the sender does not exist, I don't accept the mail.

It's an administrative option though and not enabled by default.

Chris Merrill wrote:

> Jeremy Portzer wrote:
> > You state above, "Would it not be correct to do a lookup on the
> > domain name to see if it matches the incoming IP address[...]"?
> > That would be impossible, because a server has no idea what "domain
> > name" you are connecting from.  It only knows the IP address, which it
> > gets from the TCP/IP protocol information.  It can only do one thing --
> > a reverse lookup -- to try to determine "the domain name."
>
> My knowledge of SMTP is pretty limited, but my Postfix book says that the
> first thing an SMTP server gets is the "HELO trilug.org" command which 
> identifies
> the incoming server.  It goes on to state that most servers then do a 
> reverse-DNS
> lookup (since you can't trust a spammer/hacker to give a valid 
> identity) to find
> the true origin and determine if the mail should be allowed.
>
> Wouldn't it make more sense to perform a regular DNS lookup (instead 
> of the
> reverse) to determine if the claimed domain could really be coming 
> from the
> incoming IP address?
>
> Chris
>
>