ok, I have devised a workaround for this now.
I now have yet another question about the mailserver.
When I am sending mail from outside servers towards my mailserver I get errors -
ERR: authdaemon: s_connect() failed: Permission denied Invalid user specified.
Once I encounter this error this command fixes it
chmod 4755 /var/run/courier/authdaemon
is there any way to make it so I don't recieve this error anymore