From top of the email, remove everything after
-----BEGIN PGP SIGNED MESSAGE-----
untill the first line change.
For example:
``` -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
Hi, ```
You would remove
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
so the message would be
Hi,
Remove everything between lines
-----BEGIN PGP SIGNATURE-----
and
-----END PGP SIGNATURE-----