Re: [Exim] Refuse connection if no MX for sending host

Rick Duvall wrote:
> Yeah, that's what I mean. Seems like a lot of steps, doesn't it?
>
> Maybe a better way to do this is to look at the "mail from", extract
> the domain portion of the from address, and then check to see if the
> IP of the connecting host is the MX for the domain of the sender. If
> it isn't, reject at the point of RCPT To, otherwise accept. That
> wouldn't require as many lookups in DNS at least and would be a
> little quicker.

You're making *way* too many assumptions about the SMTP topology by which
the mail got to you. You're assuming that an organisation relays outbound
mail through a server which is an MX for some particular domain it's
relaying - I don't know what percentage that is but it certainly isn't a
useful test for spam.

Peter