Yahoo and their mail filters..

Micheal Patterson micheal at
Wed Feb 25 03:53:11 UTC 2009

----- Original Message ----- 
From: "Erik (Caneris)" <erik_list at>
To: "Joe Abley" <jabley at>; "Micheal Patterson" 
<micheal at>
Cc: <nanog at>
Sent: Tuesday, February 24, 2009 9:11 PM
Subject: RE: Yahoo and their mail filters..

Ditto. They appear to use some strange form of greylisting combined with 
blocking. What seems to help is SPF and PTRs that match the EHLO your MTAs 
will send. We didn't implement Domain Keys / DKIM.

On a related note, don't get me started on Hotmail. They used to (still do?) 
silently swallow mail into a black hole after accepting it. No NDR, no spam 
folder, just good ol' mail shredding without anyone knowing. Again, SPF and 
PTRs seem to help.

Oh yeah, make sure you're not sending spam to them. That might help too. ;)


SPF records aren't being recognized, I've been running them for some time 
now so it would seem that they're not honoring them.


Micheal Patterson

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