adding text mail

It is possible to add text (or html tag) automatically to every mail messages? Incoming and outgoing messages.

Where I must do the mod?

Thanks.

 

For incoming messages you could use a procmail recipe.

 

For outgoing?

 

Maybe you can use amavisd-new for it. Or you write your own script and add it as a filter in /etc/postfix/master.cf.