RE: Advanced tricks I use to get rid of spam using MX 4xx [X200611277077]

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-----Original Message-----
From: Marc Perkel [mailto:marc@perkel.com]
Sent: Monday, November 27, 2006 5:51 PM
To: Matt Thoene
Cc: qmail@list.cr.yp.to
Subject: Re: Advanced tricks I use to get rid of spam using MX 4xx



Matt Thoene wrote:
> Hello Marc,
>
> Monday, November 27, 2006, 12:28:12 PM, you wrote:
>
>   
>>> That is correct.  Any MTA which immediately tries another delivery upon
>>> receiving a temporary deferral is broken.
>>>
>>>
>>>   
>>>       
>
>   
>> So - Qmail does it right and every other MTA does it wrong?
>>     
>
> It's been a while since I've worked with Postfix but I am pretty sure
> they too do not immediately try backups when they get a temporary
> deferral. The mail is placed in the deferred queue and tries again
> later.
>   

Nope - Postfix will immediately go up the MX list trying all servers. 
I'm sure of that because I have a test account on a Postfix server and I 
often test it. Only Qmail - and no other MTA will refuse to retry the 
higher MX on a 4xx error. I originally came here to report it as a bug 
and figured that it was only in very old qmail versions. I'm quite 
surprized to find it was deliberate and there's a cult like attachment 
to the problem.