Install amavisd-milter-dbg by entering the following commands in the terminal:
sudo apt update sudo apt install amavisd-milter-dbg
amavisd-new interface for milter-capable MTAs - debugging symbols
This package provides a milter for amavisd-new that works with Sendmail or Postfix, using the AM.PDP protocol. . This package contains the debugging symbols for amavisd-milter.