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Re: draft-daboo-srv-email

2010-01-08 10:32:36

Hi Hector,

--On January 8, 2010 12:27:12 AM -0500 Hector Santos <hsantos(_at_)santronics(_dot_)com> wrote:

This draft appears like a practical and simple proposal.  I just added a
SRV record for our winserver.com email domain.

_pop3._tcp              SRV     0 1 110 pop3.winserver.com.

OK, great!

A few comments:

1) Mail Pickup

I guess overall if I read the specs right, a MUA would do at least four
(4) lookups?  Assuming, there is a client design preference to checked
for a secured host first, the order would be:

     _pop3s._tcp.winserver.com
     _imap3s._tcp.winserver.com
     _pop3._tcp.winserver.com
     _imap._tcp.winserver.com

And no decision can be made until all four are determined to allow for
user selection idea. IOW, four queries MUST be made.  Since this would
normally be a one time thing, it doesn't present any high volume DNS
overhead issue. +1.

I believe DNS allows a server to return more records than were originally requested. What we could do is suggest that DNS servers return all the email related SRV record types defined if anyone of them is requested. However, that would require specific changes to the DNS servers to work so may be a non-starter.

2) What about outgoing?

Are MX records considered the solution?

Using GMAIL as an example, I think it only allows IMAP for receiving and
SUBMIT (port 587) for sending.  So wouldn't a SRV record be useful for
the case where SMTP is used for outgoing when the incoming uses IMAP?

The current spec defines _submission._tcp in Section 3.1 which covers email client submission server discovery.

--
Cyrus Daboo

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