Hi, I throttle my traffic to AOL and HOTMAIL, maybe you need to do the same for 
I had to lookup each ISP's limits to configure it in Postfix to help with all 
the mail to them getting deferred.

I must say it has been years since users complained about mail not getting 
delivered to those domains, and it used to be weekly.

slowaol_destination_recipient_limit = 10
slowaol_destination_concurrency_limit = 2
slowaol_destination_rate_delay = 30s

slowaol   unix  -       -       n       -       1       smtp

-Angelo Fazzina
Operating Systems Programmer / Analyst 
University of Connecticut,  UITS, SSG, Server Systems

-----Original Message-----
From: owner-postfix-us...@postfix.org [mailto:owner-postfix-us...@postfix.org] 
On Behalf Of Fongaboo
Sent: Thursday, December 1, 2016 3:36 PM
To: Postfix users <postfix-users@postfix.org>
Cc: d...@dinocovelli.com; mec...@mechno.com
Subject: Banned by Yahoo?

I've been getting a lot of these errors for mail sent to Yahoo all of a 

> 421 4.7.0 [TSS04] Messages from temporarily deferred due to 
> user complaints -; see 
> https://help.yahoo.com/kb/postmaster/SLN3434.html (in reply to MAIL FROM 
> command))

The included link states:

> Error: "421 4.7.0 [XXX] Messages from x.x.x.x temporarily deferred due 
> to user complaints -" when sending email to Yahoo
> This error indicates Yahoo is seeing unusual traffic from your IP 
> address and/or that emails from your mail server are generating 
> complaints from Yahoo Mail users.

I checked MXDomainTool and we're not on any blacklists (not that I would 
expect that to be related). But I did a thorough check for any config 
mishaps that might have us open relaying, but we are closed up tight.

However we do have virtual aliases on hosted domains that ultimately point 
to yahoo.com addresses. Undoubtedly, I can reference instances of spam 
received to the virtual and then forwarded on to Yahoo's mailserver from 

But can they really blame the middleman (us) for mail that is just passing 
through our hands? I mean, I understand it's possible for them to do 
whatever they please. But mostly just looking for a sanity check that I am 
corectly ascertaining what is happening and what they are doing?

I saw some earlier posts on a similar issue with Yahoo, but it related to 
rate-limiting rather than 4-hour bans. Not sure if it was the same 
instigating factor but they've just changed their policy...

Any ideas welcome... But also looking for a sanity check on one thing I 
was thinking of trying:

Find any virtual aliases that point to yahoo.com or ymail.com addresses... 
replace the aliases with a virtual MAILBOX that *forwards* to Yahoo. Then, 
as per my configuration, any mail destinated for yahoo will be scanned by 
Maia-Mailguard/SpamAssassin before it is allowed to leave for Yahoo.

My hope would be that once yahoo-destinated spam passing through my server 
slows down they will unban.

TIA for sanity checks!


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