By default, messages are encrypted to all recipients (
Bcc headers). Thus, you will not be able to decrypt
your own messages. To make sure that messages are also encrypted to
your own key(s), several alternative solutions exist:
encrypt-tooption in the file gpg.conf (for OpenPGP) or gpgsm.conf (for S/MIME with EasyPG). See Invoking GPG, or See Invoking GPGSM.
mml-secure-openpgp-encrypt-to-self(for OpenPGP) or
mml-secure-smime-encrypt-to-self(for S/MIME with EasyPG).