Changing mta in /etc/alternatives : how?

[Graham Cossey]

Sorry for the probably basic question, but I would like to change the
default mta on my FC2 box from sendmail to exim. I believe to do this I need
to change the 'entry' in /etc/alternatives/ to point to
/usr/sbin/sendmail.exim instead of /usr/sbin/sendmail.sendmail.

Doing a 'ls -al' on /etc/alternatives shows that the entries here are
lrwxrwxrwx, what exactly is the 'l' and how do I change it? I have tried
creating a test symbolic link such as :

ln -isv /usr/sbin/sendmail.exim test

but the colour coding of the resulting 'test' link is different to the
existing ones.

Can someone shed some light on this for me?

Many thanks

Graham