MX relay sites

[Barry Finkel]

"Gary Wardell" <gwardell at gwsystems.co.il> wrote:

>My understanding is that most SMTP mail servers, if they see an MX 
>record, will try for a few days to send mail to you.  If they
>don't see an MX record then they will give up immediately.  ...

I believe the SMTP RFCs have a different ruleset:

     1) If you see an MX record, try sending mail to that MX record.
        If there are multiple MX records, then the RFCs detail exactly
        what to do.

     2) If there are no MX records, then try sending the mail to the
        node itself.

Most mailers will retry the mail at regular intervals for a specific
length of time (usually administrator-settable).  Then they will return
the mail to the sender as undeliverable.  Note in step 2) that MX
records are not a requirement if a node handles its own mail.
----------------------------------------------------------------------
Barry S. Finkel
Electronics and Computing Technologies Division
Argonne National Laboratory          Phone:    +1 (630) 252-7277
9700 South Cass Avenue               Facsimile:+1 (630) 252-9689
Building 221, Room B236              Internet: BSFinkel at anl.gov
Argonne, IL   60439-4844             IBMMAIL:  I1004994