E-Mail scaling question

Chuck Swiger cswiger at mac.com
Tue Dec 21 20:19:57 UTC 2010

On Dec 21, 2010, at 11:39 AM, Mark Moellering wrote:
> My company needs a [new] e-mail solution for a product rollout.  Rather than 
> have a few e-mail domains with lots of addresses, the solution we need is for 
> a very few (mostly one, very rarely more than 3) accounts on upwards of tens 
> of thousands of domains.

I don't see much value in setting up tens of thousands of what sound like vanity domains, but you'll need postmaster@ working at each of these domains to be even minimally compliant with RFC-822/2822/etc, and most people expect abuse@ to work also.

> I can't find any info on scaling sendmail or postfix to this many domains.  If 
> anyone has any info, knowledge, horror stories, etc. It would be greatly 
> appreciated

You'll want to use hash table map type for sendmail's virtusertable or Postfix's virtual table-- see /usr/share/sendmail/cf/README or /usr/local/share/doc/postfix/VIRTUAL_README.

> Also, I am assuming that to play nice, we need a dedicated IP per domain, so I 
> may have to survive setting that up before I even get to the e-mail.  If 
> anyone knows of a legitimate way to set up an e-mail domain on a shared IP and 
> not have half of the e-mail servers assume we are spammers, let me know.

There's nothing unusual about having one IP serve as the MX for many domains.  After all, many hosting companies provided a shared email solution.

What matters most to spam checking is the mail contents, whether forward and reverse DNS match, whether postmaster@ and abuse@ works, and whether bounces, address verification, etc are handled properly.


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