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Article: 989
From: Anthony Howe
Date: 2006-06-29 07:25:42 -0400
Subject: Re: Looking ahead for "over quota" mailboxes

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Grant Taylor wrote:
> Quentin Campbell wrote:

> I do believe that you are underestimating the difficulties involved.  
> Now it sounds like you are wanting a relay server to be able to find out 
> if a mail box on a destination server is over quota.  To start with the 
> destination server would have to be able to tell if a mail box is over 
> quota or not, which by default Sendmail can not.  Then you are wanting 
> that destination server to report to the relay server such condition.  
 > ...

Grant has pretty well outlined the problem. milter-ahead on the gateway 
has no way of finding out the mail box quota on another system. Even 
then if it could, remember too that mail systems vary: Cyrus Imap has a 
quota system independent of disk quotas; not sure how Exchange, Exim, 
Qmail, Postfix, Groupwise, or any other MTA / mail store handles quotas.

Also you can't rely on the SMTP text response to be clear as to reason 
(consider differences in phrasing and languages). IF and ONLY IF, the 
mail store uses RFC 3463 Enhanced Mail System Status Codes, then some 
basic action might be possible for 4xx 4.2.2 and 5xx 5.2.2 numerical 
responses, but I don't see what milter-ahead can do other than what it 
already does: if the mail store reports 4xx to milter-ahead then milter 
ahead relays that status code to the connecting client, like wise for 
any 5xx. So if the mail store reports 450 4.2.2 to milter-ahead, 
milter-ahead temp. fails the client with 450 4.7.1 (the enhanced code 
2nd and 3rd level code are not relayed).

> It sounds like you are trying to help prevent back scatter.  A noble 
> cause for sure, but a difficult one.  I would be more inclined to try to 

milter-null for backscatter is coming soon (this weekend I hope). 
Preview the documentation on-line:

	http://www.snertsoft.com/sendmail/milter-null/

-- 
Anthony C Howe          Skype: SirWumpus                    SnertSoft
+33 6 11 89 73 78         AIM: SirWumpus    Sendmail Milter Solutions
http://www.snert.com/     ICQ: 7116561
     http://www.snertsoft.com/

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