It's been a long time since I set up my fetchmail (it's one of those "set and forget" things) but, IIRC, an existing, properly configured MTA is not a prerequisite, as the preliminary comment states.

 Fetchmail should hand off retrieved mail to whatever application is stipulated in the run control file. It defaults to port 25 only if it has not been given another application.

 Fetchmail can also be forced to deliver directly to the user's mail spool:

and wants mda "/usr/bin/procmail -d user"

Regards,

Robert Thorsby