I was having similar problems. I fixed it by modifying my muttrc file.
The Mutt distribution comes with a sample gpg configuration in its contrib
directory. It's called gpg.rc
. I added it all without any changes, and now I can send and receive GPG-encrypted email messages in Mutt.
These are the specific lines I added, but I recommend looking at the file yourself, since there are also some lines that are commented out, along with explanatory comments, and also it might not be correct for your version of Mutt.
set pgp_decode_command="gpg --status-fd=2 %?p?--passphrase-fd 0? --no-verbose --quiet --batch --output - %f"
set pgp_verify_command="gpg --status-fd=2 --no-verbose --quiet --batch --output - --verify %s %f"
set pgp_decrypt_command="gpg --status-fd=2 %?p?--passphrase-fd 0? --no-verbose --quiet --batch --output - %f"
set pgp_sign_command="gpg --no-verbose --batch --quiet --output - %?p?--passphrase-fd 0? --armor --detach-sign --textmode %?a?-u %a? %f"
set pgp_clearsign_command="gpg --no-verbose --batch --quiet --output - %?p?--passphrase-fd 0? --armor --textmode --clearsign %?a?-u %a? %f"
set pgp_encrypt_only_command="pgpewrap gpg --batch --quiet --no-verbose --output - --encrypt --textmode --armor --always-trust -- -r %r -- %f"
set pgp_encrypt_sign_command="pgpewrap gpg %?p?--passphrase-fd 0? --batch --quiet --no-verbose --textmode --output - --encrypt --sign %?a?-u %a? --armor --always-trust -- -r %r -- %f"
set pgp_import_command="gpg --no-verbose --import %f"
set pgp_export_command="gpg --no-verbose --export --armor %r"
set pgp_verify_key_command="gpg --verbose --batch --fingerprint --check-sigs %r"
set pgp_list_pubring_command="gpg --no-verbose --batch --quiet --with-colons --list-keys %r"
set pgp_list_secring_command="gpg --no-verbose --batch --quiet --with-colons --list-secret-keys %r"
set pgp_good_sign="^\\[GNUPG:\\] GOODSIG"