[oclug] Postfix puzzle

Glenn Henshaw thraxisp at magma.ca
Wed Sep 28 06:56:31 EDT 2005

   I'm seeing a similar thing with AOL. It appears that they add some  
rate measurements to their SPAM filter. If you send too many  
messages, they are rejected as SPAM based on originating ISP.

On 27-Sep-05, at 9:04 PM, Phil Orpen wrote:

> Hi,
> /me thinks the recipients' MTA has some funny rules...
> Things to check for:
>  - Your postfix's announced IP address... e.g.
>  - Your postfix's announced name at helo/ehlo with the other MTA.
>  - Your rdns
> Some spam filters will block any IP for a network with known IPs..  
> e.g.
> rogers' users are "supposed" to send via rogers' smtp server as a
> smarthost.  Which might be the best explaination... if your IP is  
> inside
> sympatico's network, but doesn't match smtp*.sympatico.ca...
> Your ip has an rdns assigned by sympatico and your postfix might  
> not be
> using that name at helo/ehlo.. some filters will reject when
> fqdn != rdns
> A few telnet sessions to port 25 should reveal the answer..
> In short, without knowing the rules at the other end, you might not be
> able to sort this one out..  perhaps forcing postfix to use
> smtp*.sympatico.ca as a "relayhost" will solve things for you.  Some
> documentation will call this a "smarthost"... YMMV.
> Mind you... postfix is pretty flexible..  you might be able to send
> email to some domains via smtp*.sympatico.ca and not other domains..
> Good Luck!
> -Phil
>  ----
> philip at orpen.com (Pgp: 0xB578851A)
> Freelance Linux Technician  (Need Help?)
> On 27-Sep-2005 19:20 The Linux Doctor wrote:
> | Hi Guys,
> {snip}
> | The puzzle is this. If that IP has been black listed, why would it
> | bounce the mail sent by Postfix and not by my Sylpheed client?
> {snip}
> -- 
> OCLUG general discussion list
> OCLUG at lists.oclug.on.ca
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