When I use –clearsign, the plain text has sometimes extra dashes in it – why?
This is called dash-escaped text and is required by OpenPGP. It always happens when a line starts with a dash (“-“) and is needed to make the lines that structure signature and text (i.e., “—–BEGIN PGP SIGNATURE—–“) to be the only lines that start with two dashes. If you use GnuPG to process those messages, the extra dashes are removed. Good mail clients remove those extra dashes when displaying such a message.
