I hesitate to put in a bug report because I'm just learning about all this virtualmin stuff, so it could just be me.
Under the spamassassin config module, I set it to report in the headers instead of the message body.
It looks like vm put 'report_header 1' into the local.cf file.
and that line was reported as an error.
I did a little research and it appears that item has been depreciated. I didn't quite understand what I am supposed to use in it's place though.
And even though --lint said it was ignoring that line, it doesn't really seem to be, as the report is in the headers - so I don't know, but figured I'd pass it along,