SMTP on port other than 25 through DNS???

[Mathias Körber]

> >I get an IP address through dhcp from roadrunner
> >(cable access).  I also have a second-level domain
> >name resolving to this address through dynamic DNS
> >(nameservers at easydns.com).
> >
> >Problem is that roadrunner blocks port 25 so I
> >can't get any incoming mail.=20
>=20
> I though incoming mail was on port 110 (POP3) or IMAP (not sure which
> port) SMTP on port 25 is for sending mail

He is trying to run his own mailserver, not just collect mail
from a POPserver somewhere else. Thus the incoming mails would
come via SMTP (to port 25).

And no, there is no current way to do this in DNS. MX records do not
carry port information and most MTUs have port 25 hardcoded in...

In future SRVLOC might be used to specify the port#, but until the
majority of MTUs support that you're out of luck.

>=20

> I don't know if it's a DNS issue or not; a mail server is a mail
> server, just configure it to listen on a different port and configure
> your mail client to do the same. (I think....I could be wrong, though,
> anyone can correct me if I am!!)=20

The server can listen on the other port as long as it wants to, but
how are remote mailservers trying to send him mail to know which
port that is? That is his problem!

>=20
> >I'm worried that I can't do this, but I'm out of
> >other ideas or alternate high-speed ISP's.  If
> >not, any suggestions on other ways to get around
> >this (roadrunner only blocks port 25, will unblock
> >it for additional $150/month,=20

That does sound steep, but then ADSL usually is considered
a client-access product and not for servers etc.

What you'd need is a proxy-mailserver outside that knows your
port# and just forwards all mails to you. I don't know of anyone
providing such a service...