Finding the "qualcomm.com" submission server (whether it currently
points to "submission.qualcomm.com" on port 587 or
"outgoing.qualcomm.com" on port 25) is not addressed by zeroconf.
Zeroconf addresses finding "the submission server on *this* network".
But for those networks that enforce a local submission server, zeroconf
is a more practical solution from the discovery side. SRV helps with
the "submit here based upon the domain part of your address. If the
local network (insanely) blocks outgoing submission connections, how
can you discover which SRV record to look up? (in-addr.arpa as
mentioned is one choice. zeroconf is a simpler solution, though, IMO.)
I am at a loss to figure out what problem mobile-ip addresses in this
space, but it is certainly not in the scope of the current discussion.
Mobile-ip addresses the issues that John brought up about roaming
The bottom line is that SRV cannot help here. Submission is by
definition an authenticated service that authenticates to a specific
set of servers, and therefore must be hand-configured into the client.
(And if there are several servers the client can submit to, a CNAME
will solve that problem.) This only needs to be done once, so I don't
understand why it's even an issue.