Can delete a message automatically without sending it to the trash Rated 5 out of 5 stars
/* delete skip trash */
let hdr = msgHdrs.queryElementAt(0, Ci.nsIMsgDBHdr);
hdr.folder.deleteMessages(msgHdrs, msgWindow, true, false, null, false);
Maybe I should have posted it to FiltaQuilla's forum, but if someone looks for an extension with this functionality, won't get to that forum.