Apologies if this is addressed somewhere in the docs - I haven't found
it!

I am testing out signing of messages. I set
(add-hook 'message-setup-hook mml-secure-message-sign-pgpmime)
As per the docs, and I can send a message and it gets signed. When I
view the message (which was Bcc'd to me) and hit $, I see this message:

[ Unknown key ID 0x2747EC48A98D4AF0 or unsupported algorithm ]

I click on it, and it requests _my_ public key from the key server, and
of course nothing changes - because I already had the key.

Any ideas? Is this because of some missing package or misconfigured
setting? I'm using the latest released version of notmuch (0.15.2),
emacs 24.2.1, and gpg 1.4.11.

Thanks!