discourse reply by e-mail broken

Is it possibly to reply by mail with pgp signed message?
I couldn’t make it work (mail sent today 08 Nov).

I replied by mail to grass presentation - #5 by h3xagonal with contents “Test signed message by mail.”, sent to Whonix Forum discoursereplies+5d0c914d70dcc4af8fda7beef221296d@whonix.org, but the mail didn’t appear on the thread, although for other replies I made by mail to other threads (unsigned), the replied appeared.
Maybe there is a filter?

Can you check on the mail server what happened to the message? I retried already a second time.