Polonium currently adds spamassassin headers to any message with a score >1, but only identify messages as spam with a score >4 (something close to this)

Google Support curiously suggested that our headers saying that a mail was NOT spam, might be influencing their spam detection systems.

To quote them:

"""
After checking the headers you have sent me we could determined that the Spam detection software, running on the system "polonium.wikimedia.org", is trusting this emails and therefore Google is trusting them as well, [....] you could disable the spam filtering from your server because some how they are approving those messages and interfering with Google spam filters as shown on this headers: X-Spam-Report: Spam detection software, running on the system
"polonium.wikimedia.org",
has NOT identified this incoming email as spam. The original
message has been attached to this so you can view it or label
similar future email. If you have any questions, see
the administrator of that system for details.
"""

Would it be possible to tweak these settings to NOT apply the header unless it's believed to be spam?

1. Add spam headers if score >= 1 warn spam = nonexistent:true condition = ${if >{$spam_score_int}{10}{1}{0}} set acl_m0 = $spam_score ($spam_bar) set acl_m1 = $spam_report

See also: https://phabricator.wikimedia.org/T110761

Cheers,

Joel