Had hoped for a golden solution to my problem. 
Well I'm a bit wiser now, but I still don't know how to solve the problem if
other isp's do the same. I don't think my chances, to make Symantec or
Ipswitch change the behavior, are very good.

Well thanx Scott.

CP

-----Original Message-----
From: R. Scott Perry [mailto:[EMAIL PROTECTED]] 
Sent: 28. februar 2002 16:12
To: [EMAIL PROTECTED]
Subject: RE: [IMail Forum] Imail do not send mail to backup mailservers



>Strange, if you look at RFC821 4.3 page 37 "Command-Reply Sequences":
>
>             CONNECTION ESTABLISHMENT
>                S: 220
>                F: 421
>
>That means that Symantec Firewall only can reply 421 to Imail if there 
>is a error before HELO.
>
>Correct??

RFC2821 4.3.2 updates RFC821 to allow a 554 response (although I don't 
believe 2821 is technically a standard yet).

So the two ways that it can be handled properly are [1] Send a 
554 response 
(which some mailservers may not handle correctly), [2] Send a 
421 (in which 
case mailservers should try again later with the same 
mailserver), or [3] 
Don't accept the connection.

In the case of the huge ISP, the best answer would be for them 
to take out 
the primary MX record (since it is designed not to accept mail, it 
definitely should not be in the MX record).  If they still want 
it listed 
in the MX record, and feel that the extra bandwidth is acceptable, the 
should simply drop the connection (which uses the least 
bandwidth).  Otherwise, they can use the 554 (which uses more 
bandwidth and 
some mailservers may not handle correctly) or keep using 421 
(which uses 
lots more bandwidth and will cause lots of their mail to bounce).

                                                    -Scott
---
Declude: Anti-virus, Anti-spam and Anti-hijacking solutions for 
IMail.  http://www.declude.com

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