send e-mail without use sendmail

Ed Greshko Ed.Greshko at
Thu Nov 1 02:54:56 UTC 2007

Frank Cox wrote:
> On Wed, 31 Oct 2007 12:05:11 -0500
> Les Mikesell <lesmikesell at> wrote:
>> You must have a real domain name to send email. 
> Is there any technical reason (other than "we hate spammers") why email can't
> be sent to an IP address instead of a domain name?
> I know that mail sent to joeblow at 123.456.789.001 doesn't work, but have never
> really understood why...

It is call "fault tolerance".  In general, sending to a single IP address is
has a single point of failure.  If that system is doesn't move.
 When you send to there is what is known as an MX record that
returns all the IP addresses that accept email for and weights
for the sending side to decided who to sent to first and failing that
second, etc.

Sending to IP addresses doesn't scale and isn't manageable.

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