RFC 974 Mail routing and the domain system (MX records)

http://www.ietf.org/rfc/rfc974.txt
The purpose of this memo is to explain how mailers are to decide how to route a message addressed to a given Internet domain name. This involves a discussion of how mailers interpret MX RRs, which are used for message routing. Note that this memo makes no statement about how mailers are to deal with MB and MG RRs, which are used for interpreting mailbox names.

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When a .net app, sending mail, tries to resolve the location of the smtpserver variable, does it do an MX lookup first, and then try for an A record? I think that's how the RFC is written. The dns name that I have configured as my smtpserver variable doesn't have an A record. Seems to go aginst how I know the application flow of a piece of mail to go, but after reading the RFC, and talking to my mail folks, I think its correct.

Your smtp server (the first hop) DOESN'T have to have an A record. How does your host/app resolve it then? As the RFC is written, and how I've discovered most mail clients work, the sending application (a webmail form, or outlook, eudora, whatever) should first do an MX lookup on its "smtp server" (not the domain of the destination address), and if it gets nothing, it tries for an A record.

My question is this. Do the .net components/objects do this?

John Kirkman [ kirkiezi ( at ) yahoo dot com ], 2005-08-05 09:03:24 #

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