MTAs used

Scott Berkman scott at
Wed Aug 26 17:43:26 CDT 2009

If I had to guess..


Beyond those you'd probably see a lot of the free webmail carriers (Gmail,
yahoo, and hotmail/live all use "custom" MTA's) as well as IPSwitch's iMail
and the Windows Server/IIS SMTP service.


-----Original Message-----
From: Deepak Jain [mailto:deepak at] 
Sent: Wednesday, August 26, 2009 4:10 PM
To: Valdis.Kletnieks at; Sharef Mustafa
Cc: nanog at
Subject: RE: MTAs used

> Now, did you want that in terms of "number of copies installed" or
> "amount of mail handled"?   There's probably zillions of little Fedora
> and
> Ubuntu boxes running whatever MTA came off the disk that are handling 1
> or 2 pieces of mail a day, and then there's whatever backends are used
> by MSN/Hotmail, Yahoo, AOL, etc.  "This MTA packed by weight, not by
> volume.
> Some settling of contents may have occurred during shipping and
> spamming."
> (Seriously - if 95% of the mail out there is spam, then the top 4-5
> MTAs are probably the ratware that's sending out the spam.  Something
> to consider...)

In keeping with this concept, and turning it around. What MTA is exposed to
the most spam? (1-x) That should tell you what MTA handles the most "good"
mail by also being the destination for the most spam (good, live

Or I could be missing something well known about mail flows.


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