Keep X-Spam-... header lines when releasing message from quarantine?

[Rich Wales]

Hi.  I'm using amavisd-new 2.10.1 on an Ubuntu 16.04 server, with a
heavily modified MailZu to manage my spam quarantine.

If I decide a quarantined message is not spam after all, and release it,
the X-Virus-Scanned header line and all the X-Spam-... header lines are
stripped out before the message is delivered.  Is there any way to
disable this action, so that these header lines will remain in the
released e-mail as it is delivered?

Rich Wales
richw at richw.org