[Mimedefang] Sender validation

[Jonas Eckerman]

On Thu, 24 Jun 2004 13:12:36 -0400 (EDT), David F. Skoll wrote:

>  See the thread at [...] for some pitfalls.

Thanks for the link.

That thread seems to mostly deal with <> and postmaster. I don't try to validate <> or postmaster at .*. My current list of patterns to validate looks like this:

	if ($sender !~ /^<?>?$/ && $sender !~ /^<?(postmaster|abuse)@/i && $sender !~ /^<?(|.*[-_+=])(daemon|gateway)(|[-_+=].*)@/i &&
			$sender !~ /@(|[^@]+\.)(bounces?|returns?|lists?|newsletters?)\.[^@\.]+\.[^@\.]+[^@]*$/i &&
			($sender !~ /^<?(|.*[-_+=])(anonymous|undisclosed|unspecified|lists?|returns?|users|bounces?|\d+)(|[-_+=].*)@/i ||
			$sender !~ /^<?(|.*[-_+=])$OurDomains(|[-_+=].*)@/i)) {

As you can see there's a bunch of addresses I don't validate. This is for completely separate reasons:

1: Addresses like mailer-daemon at .* are normal sender addresses even when if you can't actually send mail to that address.

2: Addresses like hiho at lists.roaringpenguin.com might be fake, but I don't want to make a too big impact on hard working list servers.

3: Addresses like abuse at .* might be faked, but they usually work so I don't want to spend time validating them.

This means that there's a whole bunch of addresses I never try to validate, but a grep -c tells me there's still a bunch of mails that will be rejected in"filter_recipient" if I start rejecting on this criteria, and so far with *no* FPs (still watching though).

(I'm going to remember that bit about rejecting from <> to multiple recipients (after DATA). Even if it only catches a few spams (does it?), it'd be such a small addition to the filter's code that it'd be worth it...)

/Jonas

-- 
Jonas Eckerman, jonas_lists at frukt.org
http://www.fsdb.org/