Test mail messages contain the complete header.
When testing amavisd, they must not be encapsulated
in another mail wrapper or otherwise modified.

Instead, feed them to sendmail (or its lookalike):

$ sendmail -i your-address@example.com <sample-virus-simple.txt
$ sendmail -i your-address@example.com <sample-virus-nested.txt
$ sendmail -i your-address@example.com <sample-nonspam.txt
$ sendmail -i your-address@example.com <sample-spam-GTUBE-junk.txt
$ sendmail -i your-address@example.com <sample-spam-GTUBE-nojunk.txt
$ sendmail -i your-address@example.com <sample-spam.txt   # old sample
$ sendmail -i your-address@example.com <sample-42-mail-bomb.txt
