signature-encryption mails are problemtic in Thunderbird

[Sven Hartrumpf]

Hi all.

signature-encryption mails (shown as PSPE in mew) are not recognized
completely in Thunderbird (the signature is not recognized as a signature).
Here is the structure that mew generates for my mails (only showing the
differing part, i.e. the signature part):

Content-Type: application/pgp-signature
Content-Transfer-Encoding: 7bit

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1
...
-----END PGP SIGNATURE-----

And here is what Thunderbird/Enigmail generates when sending equivalent mails:

Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.22 (MingW32)
Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/
...
-----END PGP SIGNATURE-----

Any ideas?
Sven