2 messages in net.sourceforge.lists.courier-users[courier-users] Re: Multiple filterin...
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Chris StassenJul 17, 2001 9:50 pm 
Sam VarshavchikJul 18, 2001 2:35 pm 
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Subject:[courier-users] Re: Multiple filtering questionsActions...
From:Sam Varshavchik (mrs@courier-mta.com)
Date:Jul 18, 2001 2:35:33 pm
List:net.sourceforge.lists.courier-users

Chris Stassen writes:

A virtual domain address points to joe (jos@virtual.dom -> joe) Joe has a ".courier-xyzzy" file to receive "joe-@example.com".

Will Joe also receive "jose@virtual.dom", or will ESMTPD claim that's not a legal recipient?

This is a nonexistent recipient.

------------------------------------------------------------- 2. Interplay between single-owner virtuals and RCPT TO legality

Let's say that... I'm "example.com" I have a local user "joe" An entire virtual domain is aliased to him (@virtual.dom -> joe) so that "fr@virtual.dom" is delivered locally to "joe-fred".

Will ESMTPD balk at any RCPT address in virtual.dom, EXCEPT ones for which Joe has a ".courier-xxxx" file? Or will it accept them and the message will bounce after being taken in?

If the home directory is globally readable, nonexistent addresses will be refused by courieresmtpd. With the home directory unreadable everything will be accepted, and sorted out later.

If Joe has a .courier-default file, will every address in the virtual domain be delivered to him? Or does the dot-courier "default" only work with one additional word (i.e.,

Well, in this case, fo@virtual.dom becomes joe-foo, so there's already one extra word in every case.

------------------------------------------------------------- 3. ".mailfilter" vs RCPT address

The ".mailfilter" language doesn't seem to have visibility of the RCPT address ("envelope to address"), which would be useful for sorting mail when multiple accounts forward to one final location, while "dot-courier" files definitely do have that info.

Actually it does, sort of. MAILFILTER.

------------------------------------------------------------- 4. Filtering before BODY

ESMTPD can be configured (smtpaccess) to refuse connections from ranges of IP addresses. But that is the only "early" (prior to accepting the message body) filtering that I'm aware of. "Global mail filters" seem to be activated once the entire message is received.

Does ESMTPD come with ways to reject messages BEFORE the body is received based on... a) reverse DNS of sending machine? (e.g., I might decide that I don't want mail from "*.KR", "*.CN", "*.AR", or "*.BR")

Only by writing this rule into an individual rcptfilter.

b) HELO name of sending machine? (e.g., "oemcomputer", anything that doesn't resolve, or "*.messagemedia.com")

No.

c) MAIL FROM address? (e.g., "*@HotStockPicks.com")

You can filter on this by using SENDER in an individual rcptfilter.

Also, I'm making heavy use of smtpaccess, and would like (it may work, but the documentation doesn't mention it) netmask and bitwise network identification a la tcp wrappers (e.g., "4.3.2.128/25" or "4.3.2.1/255.255.255.128"). The documentation indicates that one may mark a class-[ABC] network, by leaving off rightmost number(s) from the dotted quad, but in a few cases I've had to create a lot of very similar entries to nuke a /25 or /26, without taking out the rest of the class-C.

CIDR notation is implemented in the development version, as a preprocessor for smtpaccess.

-- Sam