[Info-vax] SMTP server using port 587 outgoing?

[snowshoe]

Can anyone tell me the magic words to speak to SMTP to get it to use my 
ISP's outgoing mail server on port 587 (not port 25, which is blocked)?
I don't have a recent version of the White Wall and Google is useless.

It uses SMTP AUTH which means I have to supply the ISP user/password
combo as well as an outgoing mail server name/address.

Right now, the default is direct to MX on port 25 which is blocked, so 
no mail gets out.  This is a hobby system.  Thanks in advance.