How can I add 'email scanned for viruses' to the emails

I have a small, Opensuse-based computer for my family, which includes GUI, Postfix, amavis, clamd & spamassassin. I noticed that Amavis adds a line among the hidden headers: X-Virus-Scanned: amavisd-new at mycomputer.mydomain.pl Now, I also noticed that some of the incoming emails have similar messages also in the body text, visible to the reader, after the sender's signature. How can I set up my system to add a similar notification in the body text as well?