SMTP on port other than 25 through DNS???

[Kevin Darcy]

Barry Margolin wrote:

> In article <9359ki$1cm at pub3.rc.vix.com>, count0 <tim at timmy.ws> wrote:
> >
> >
> >>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.
> >
> >I though incoming mail was on port 110 (POP3) or IMAP (not sure which
> >port) SMTP on port 25 is for sending mail
>
> He means someone sending mail to his machine using SMTP.
>
> >
> >> I was wondering if I
> >>might be able to alter the MX record in the
> >>nameserver to specify an alternative port in
> >>addition to my hostname, and then I could have my
> >>MTA listening in on that port.
>
> No, there's currently no way to tell all the other mail servers in the
> world that you're using a nonstandard port for SMTP service.  This might be
> doable in the future with SRV records, but mail systems don't currently
> look at them (and since MX records do just about everything that SRV
> records do except specifying alternate ports, there's a good chance this
> will never change).

Some folks might also find the ability to weight targets quite appealing. But MX
record usage is *very* entrenched in mail software. I wouldn't expect change
anytime soon.


- Kevin