return 1 if (! $user ) or ( $user eq '' );     # No user!
return 2 if (! $domain ) or ( $domain eq '' ); # No domain!

# The second part of these lines is *never* looked at. If $user =''
# then !$user is true and they return without ever evaluating the 
# bit past the or. You don't need the parents either.

return 1 if ! $user ;  # No user!
return 2 if ! $domain; # No domain!

# The if ! (if-not) syntax is what unless was invented for

return 1 unless $user;   # No user!
return 2 unless $domain; # No domain!