Does smtplib lookup MX records?

Donn Cave donn at u.washington.edu
Fri Nov 16 18:27:06 CET 2001


Quoth Dale Strickland-Clark <dale at riverhall.NOTHANKS.co.uk>:
| I've been trying to send emails with smtplib and had a large number of
| failures. Investigation seems to reveal the the smtplib module does a
| simple connect passing the hostname to socket.connect without trying
| to resolve the MX record.
|
| In some cases this works where the mail server happens to have an
| A-type DNS record anyway but otherwise it fails with a connection
| error.
|
| Is this really the case?

Yes.

| If it is, what do I need to do to lookup the MX record myself?

I have never used it for anything, but you can find a Python DNS
client implementation in the source directory Demo/dns, if that
helps.  Note that you have to specify the DNS server, and you'll
have to decide who that is somehow according to site & platform.
You may find that it will in turn refer you to another authoritative
DNS server where you get the answer.

A C module that calls res_search() would be another option.

	Donn Cave, donn at u.washington.edu



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