On 5/14/2004 4:32 PM, Douglas Otis sent forth electrons to convey:
Here is an early link to a draft submitted to the IETF utilizing the DNS
SRV record to publish authorized clients for any protocol including
SMTP. This draft also suggests the label for this SRV record can be
used to access a TXT record for error reporting information. This was
to provide a foundation for a solution independent of how the
information is used. This takes advantage of existing DNS listing and
reporting features while not creating a record possibly confused as
pointing to an SMTP server.
http://www.mail-abuse.com/public/draft-dougotis-SRV-CAA-00.txt
Our name server was modified recently so it may take some time to access
to this link. If so, try-
http://204.152.185.196/public/draft-dougotis-SRV-CAA-00.txt
-Doug
Interesting.
In other words,
something like
"dig _smtp._tcp_c.example.com SRV"
is done by an SMTP server receiving email from a client.
It's not defined where "example.com" came from. (derived fom return
path, HELO, rDNS...)
It perhaps returns something like
...
;; ANSWER SECTION:
example.com. 3600 IN SRV fred.example.com.
example.com. 3600 IN SRV sam.example.com.
;; AUTHORITY SECTION:
fred.example.com. 3600 IN A 172.30.79.11
sam.example.com. 3600 IN A 172.30.79.12
...
?
And if the client's IP is listed, then it is authorized by the domain
administrator to send email.
A domain with a large number of ns and mail servers might be in trouble,
no?
Say 8 RR's are returned, each of which reasolves to 8 A records (this is
about the max in 512B packets)
So the domain can have at most ~64 mail servers. Or am I missing
something?
FYI, ZoneEdit (who does DNS for my domin and many others) doesn't
support SRV, though they do support TXT.