command line to restart smtp interface?

Is there a commandline to restart the smtp interface module?

I assume there must be, as the Module Status screen in SMG Administration has a button to restart smg-smtp which undoubtedly executes a commandline to do the restart.  I tried "service smg-smtp restart", but it says "no such service smg-smtp".  I know I could do "service smg restart" to restart the whole shebang, but I'd like to do just the smtp module.

As usual, the documentation is lacking.