systemd misses services

[Haines Brown <haines@histomat.net>]

I did a new install of debian and find that exim and spamassassin are not recognized 
services. That is, in /etc/systemd/system/ exim and spanassassin are not listed.

So when I do

  # systemctl start exim.service
  RROR:systemctl:Unit exim.service could not be found.

This no help:

# systemctl enable exim.service
ERROR:systemctl:Unit exim.service could not be found.

#  systemctl start exim
ERROR:systemctl:Unit exim.service could not be found.

Why are exim and spamassassin automatically present as services?

-- 

     Haines Brown