Re: [Exim] conditionally rejecting <> sender

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Author: Chris Edwards
Date:  
To: exim-users
Subject: Re: [Exim] conditionally rejecting <> sender
On Wed, 9 Apr 2003, John Jetmore wrote:

|
| I saw this in a rcpt acl posted in another email:

|
|   deny  message   = Only one receipient accepted for NULL sender
|         senders   = :
|         condition     = ${if >{$rcpt_count}{1} {1}}

|
| Since there are a lot of people on the list with some very strong feelings
| about how email should behave, I was wondering what people thought of
| this. It would certainly start preventing spam around here, just not sure
| if there's a case I'm missing where that's valid...


Messages sent *from* a list address might trip this - suppose:

- alias "support" at our site goes to users "fred" and "jim"

Fred sends a mail to some remote destination on the internet, using
envelope sender "support". Remote server somewhere out on the internet
fails this message for some reason, generating a bounce destined for
"support". Our site MX expands support into fred+jim and delivers to the
internal messagestore server hosting both fred and jim. If the internal
messagestore server enforces the above ACL, the legit bounce message will
be rejected.

I guess the solution is simply to only have this ACL on the MX machines,
(only checking bounces coming in from remote hosts).


--
Chris Edwards, Glasgow University Computing Service