From [clamav-users] Tilman Schmidt <tschmidt@cardtech.de>:

ClamAV running on Ubuntu Xenial, package version
0.99.2+dfsg-0ubuntu0.16.04.2, emits the following warning message when
scanning one of my Thunderbird IMAP mail folders:

LibClamAV Warning: Unsupported message format `http' - if you believe
this file contains a virus, submit it to www.clamav.net

I whittled it down to a specific mail message which contained in its
body an HTTP header including the line "Content-Type: message/http"
(quite legitimately - it was a discussion of a web server's behaviour)
and have produced a minimal file (25 lines, 773 bytes) exhibiting the
problem.

IMHO this warning is spurious. The file in question does not in fact
contain anything in "message format `http'".

How can I contribute to getting this fixed?
Anyone interested in my minimal sample file?

Thanks,
Tilman