[exim] SMTP - set port and auth

Hello all,

I have several servers that are using exim as their default MTA upon
installation.

This server is set to send all system emails to user@??? (which
exists on a public web/email server).

To send email through that server, a user has to send to mail.domain.com on
port 1234 (ie, not port 25).

The user must also authenticate using their full email address (
user@???) and password.

I am only using this so that the support user can receive daily emails from
the server about various services that are running, etc.

In the exim.conf file, how do I set exim to use this port 1234 rather than
the standard port 25? I have tried mail.domain.com:1234 - but that did not
work.

My current router is:

send_upstream:
driver = manualroute
transport = remote_smtp
route_list = !+local_domains mail.domain.com:1234

However, when I try testing to see if I am even communicating on port 1234,
I use the following command:

# exim -v -odf user (here, the user's alias/email address is set to
user@???)
# This is a test!
# .

At this point, the attempt begins to send an email. However, I see this in
the output:

Connecting to mail.domain.com [123.123.123.123]:25 ... connected

So, the line:

route_list = !+local_domains mail.domain.com:1234

is apparently not the way to do this. So, what is the proper way?

And then on the second part of this, how do I get exim to connect using the
single user@??? and password whenever it attempts to route mail
through the mail.domain.com SMTP server?

Thanks for any and all direction on this!