Can I redirect port 25 with a dynamic dns service?

[Bill Horne]

Sorry if this is a dup: I posted the question before, but it's not in 
the archives, so here it is again.

I'm using dyndns.org to redirect port 80 traffic to my server, but I'd 
like to get port 25 going again too and I'd like alternatives to 
dyndns.org's Mail Hop service.

Which dynamic DNS services will map port 25 to something else? Comcast 
is blocking SMTP at my locaiton, so I need a workaround.

TIA.

Bill Horne