[Mailman-Users] Comcast, Yahoo, Hotmail blocking us

Jeffrey Goldberg jeffrey at goldmark.org
Sun Sep 2 19:26:28 CEST 2007

On Sep 1, 2007, at 1:09 PM, Mark Sapiro wrote:

> I suppose that's possible, but before going down that road, I would
> make sure that the domain that the server identifies itself as in SMTP
> HELO or EHLO is the same domain returned by an rDNS lookup of its IP
> address.

Let me add to this.  I fully agree that there are DNS related things  
that can and should be done to make a legitimate mailing list system  
less likely to be blacklisted.

I run a mailing list server at  Before I set that up I  
had to have the rDNS (aka PTR record) for that IP changed from




Doing this was the hardest part of the job because it took two  
painful hours on the phone with Verizon Business Internet support.   
However painful that was, it really was necessary.  I would not have  
set up a mailing list server until I had that sorted out.

I also have SPF records for all of the domains that might appear in  
HELO or MAIL FROM addresses for anything coming off of my net.   
Having a proper rDNS and SPF records to match should demonstrate to  
most reasonable systems that the mail from my IP really is under my  
(fully traceable) control.

Of course I have postmaster and abuse addresses working for all of  
the domains that mail may come from.

Still, with all of this, I got blocked by 1and1.com as being a  
dynamic address (which of course I'm not).  What was also annoying  
was that 1and1.com rejected the mail with a 4xx, so the mail just sat  
in my outgoing queue, retrying every now and then until I removed the  
messages from the queue.

It took several attempts to contact 1and1.com support (they don't  
publish a telephone number for non-customers) before this finally got  

But other than that, I've had no problems with comcast, yahoo or  
hotmail and only minimal problems with AOL.

AOL has a document on the web someplace about what they want from  
mailing list providers.  Most of their requirements are pretty much  
what people should be doing anyway.

This is a long winded way of saying that before looking at exotic  
solutions like throttling, there are other steps you should be taking  
anyway that may resolve the problems.


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