On 3/16/04 at 4:22 PM -0600, Eric A. Hall wrote:
Cool. Always good to read documents; I have to pay more attention.
:-) In there, you write:
b. Extract the mail domain element from the user's email
address, and append the "_submission" and "_tcp" labels to
the left of that domain name.
Have any of the big ISPs deployed the appropriate records to try this yet?
On 3/16/04 at 5:33 PM -0500, Keith Moore wrote:
Is anyone implementing SRV records for either SMTP or for Submission
(i.e., SMTP SUBMIT extension)? Some talk about implementation raised
I hope that nobody is doing this in shipping product.
Not that I know of. This was talk about what could (and should) be
desirable as a future feature.
For instance even if there were SRV records pointing to an SMTP
server, existing clients would not recognize them - they would be
looking for MX or A (or perhaps AAAA) records. And new SRV-aware
clients would behave differently than existing clients, leading to
more difficulty in tracking down problems.
I was actually more interested in whether anyone was doing something
like this internally for relaying between internal machines that used
alternate ports for only that purpose. I didn't really imagine that
this would be a good thing to transition to in order to replace MX in
the bigger picture.
- SRV for submission is an interesting way for an client to figure
out which server/port it should contact, but what exactly would the
query look like?
SRV for submission is slightly more interesting. I don't see the
harm in using SRV as part of an MUA configuration mechanism as long
as it's always possible for the user to override the settings. For
a variety of reasons it's not always reasonable to use a submission
server associated with a From address, but it might be a useful way
to supply defaults.
That's what I was looking for.
(It's _much_ less reasonable to base the query on the source IP
address. The last thing we need is more location-specific variation
in network behavior.)
I thought you'd like that suggestion, Keith. ;-)
Offhand, it seems like just solving the configuration problem for
mail submission is too much work for too little gain.
It seems to me if (e.g.) Hotmail (or even a large corporate network)
could deploy an SRV for their submission servers (round-robin'ed or
weighted appropriately) and clients supported the SRV, that would be
a lot of bang for the buck in simplifying the most straightforward
What you'd really like to do is solve the entire MUA configuration problem.
That's what ACAP was supposed to do, but it hasn't gotten much
traction, I think at least in part because it tried to solve the
SRV might be part of the picture, but trying to do all of this with
SRV seems like a tall order.
I think it might address this particular config problem (and perhaps
POP/IMAP server) quite well.
Pete Resnick <http://www.qualcomm.com/~presnick/>
QUALCOMM Incorporated - Direct phone: (858)651-4478, Fax: (858)651-1102