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Postfix Archives: Allowing only valid (deliverable) sender addr

Allowing only valid (deliverable) sender address for outgoing mail

Subject: Allowing only valid (deliverable) sender address for outgoing mail
From: Mark Martinec (Mark.Martinecijs.si)
Date: Mon Jan 10 2000 - 07:26:58 CST

I need an advice on how to tighten up Postfix on the main mail gateway
so that it would only allow outgoing mail sent with a valid (deliverable)
'From:' address, which is of the form Name.Surnamedomain
(the problem arises when mail is forwarded by internal hosts - see below).

Our internal hosts generate the sender address either of the form
usernamehost.domain (workstations) or as Name.Surnamedomain (PCs).
The first form is translated by sender_canonical_maps on the gateway
to external form (Name.Surnamedomain). The second form is assumed
to already be in the correct external form. [Btw, the 'username' part
is host specific for historical reasons - i.e. there may be another user
on a different internal workstation with the same username.]

I tried to provide a list (a map) of all valid internal as well as
all external canonical e-mail addresses to limit the sender address
for the outgoing mail (recognized as outgoing when originating
from mynetworks). This worked fine with one exception:

The problem is when a user on an internal host creates a forwarding
address on his mailer to resend the mail he receives to some foreign host
(if forwarding is done by central mail gateway all is fine).
In this case the forwarded mail is (re-)originating from the
internal host, yet the sender address is foreign. My mail gateway
should allow this outgoing mail, but I don't know how to
describe/pinpoint this type of resent messages to Postfix.

Regards
   Mark 

-- 
  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  !!  Mark Martinec (system manager)     tel +386 61 177-3575 !!
  !!  J. Stefan Institute, Jamova 39     fax +386 61  219-385 !!
  !!  SI-1000 Ljubljana, Slovenia    mark.martinecnsc.ijs.si !!
  !!!!!!!!!!!!!!!!!!!!!!!!!! http://www.ijs.si/people/mark/ !!!!

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