MTAs used

James Hess mysidia at
Wed Aug 26 19:46:06 CDT 2009

On Wed, Aug 26, 2009 at 3:01 PM, <Valdis.Kletnieks at> wrote:
> (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...)
Some of the most popular:
1. Sendmail; (24%)
2. Postfix (20%)
3. Qmail (17%)
4. Microsoft Mail

In all fairness, the ratware  programs that send out spam are usually
MUAs, not MTAs, [RFC2476].
"Message Transfer Agent (MTA) --
   A process which conforms to [SMTP-MTA], which acts as an SMTP server
   to accept messages from an MSA or another MTA"

SMTP server installs that do not accept mail from other servers might be MSAs
but are not MTAs.
(The default mail server installed in Fedora doesn't count as a MTA,
unless reconfigured to listen on some network interface, because the
default config only accepts a SMTP connection from a local MUA using
network loopback.)


More information about the NANOG mailing list