Bug#265390: to smarthost via port 587

[Dan Jacobson]

Gentlemen, my free ISP will soon blockade port 25. How shall I then
get to my smarthost?  However my smarthost has opened port 587 just
for me. However, (on Debian) [names changed to protect]
dc_smarthost='fraudo.snoresh.net::587:porky.softstools.com'
gives "no IP address found for host fraudo.snoresh.net:587"
I thought it would then try the backup at softstools.com, but no.
Anyways my lack of knowledge combined with this being Debian might
soon leave me in read only mode as far as email goes. Help. How does
one tell exim to use a different port number? Single colon: no. Read
spec, tied double colon, no.
$ grep DCsmarthost /var/lib/exim4/config.autogenerated
DCsmarthost = fraudo.snoresh.net
  route_list = * DCsmarthost byname
  hosts_try_auth = ${if exists {CONFDIR/passwd.client}{DCsmarthost}{}}
Is it the byname that is ruining my life?