- See if /lib/systemd/system/clamd@.service exists.
- Read it in using SafeConfigParser.
- Determine if a section [Install] exists.
- If it does not, write out /etc/systemd/system/clamd@.service with an added [Install] section (WantedBy=multi-user.target should do it).
Do this before issuing a systemctl start clamd@amavisd and/or systemctl enable clamd@amavisd.
Distributions that use systemd but do not have the problem for ClamAV may need to be treated separate.