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  1.  Home
  2. WEB400
  3. January 2006

Re: DNS Lookups

Scott,

I agree that you may have to do step (a), I was a little to aggressive
about that, but it MUST NOT be first. Re-read RFC2821, section 5:

"The lookup first attempts to locate an MX record associated with the
name. ... If one or more MX RRs are found for a given name, SMTP systems
MUST NOT utilize any A RRs associated with that name unless they are
located using the MX RRs..."

So, per the RFC, you MUST check for MX records first, and only use A
records if MX records are not found. 

-Walden

------------
Walden H Leverich III
Tech Software
(516) 627-3800 x3051
WaldenL@xxxxxxxxxxxxxxx
http://www.TechSoftInc.com

Quiquid latine dictum sit altum viditur.
(Whatever is said in Latin seems profound.)

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