Since I have an example around I'll paste that - there are other ways
of doing this though, and you may not want to use this particular one
if you talk to more than one SMTP server....
# router
# NB no other router uses the same transport
smart_route:
driver = manualroute
route_list = \
* 1.2.3.4 byname
transport = auth_smtp
# transport
auth_smtp:
driver = smtp
hosts_require_auth = *
# authenticator
cram:
driver = cram_md5
public_name = CRAM-MD5
client_name = myusername
client_secret = mypassword
