Simple Mutt config for using GnuPG via GPGME

gpg.rc

# Old-school GPG config was taken from the following docs. I'm preserving these
# links here just in case I need to configure an old version of mutt & gnupg in
# the future without gpgme.
#   * /usr/share/docs/mutt/gpg.rc
#   * http://codesorcery.net/old/mutt/mutt-gnupg-howto
#   * http://dev.mutt.org/trac/wiki/MuttGuide/UseGPG
#
# Mutt now has solid support for GPGME, which not only makes config much
# simpler and eliminates the need to fork gpg processes & parse their output -
# it also makes working with gpg-agent, kwallet, gnome-keyring etc. a doddle
# (i.e.  automatic)
#
# This does of course all assume that gnupg is configured correctly, so check
# ~/.gnupg/gpg.conf and make sure commands like `gpg --list-secret-keys` and
# `gpg --search-keys 0xBE0E47FC` work as expected.
#
# Mutt needs to be built with gpgme support for this to work:
#     mutt -v | grep -i gpgme
set crypt_use_gpgme=yes

# Automatically sign all outgoing messages
set crypt_autosign=yes

# Automatically verify the sig of a message when opened
set crypt_verify_sig=yes

# Automatically sign replies to messages which are signed
# Automatically encrypt replies to messages which are encrypted
# Automatically sign replies to messages which are encrypted
set crypt_replysign=yes
set crypt_replyencrypt=yes
set crypt_replysignencrypted=yes

# This enables the new PKA method of key validation via DNS. It's currently
# very rare, but doesn't hurt to enable & test it. See the following links for
# more details:
#   http://lists.gnupg.org/pipermail/gnupg-devel/2005-August/022254.html
#   https://www.df7cb.de/blog/2007/openpgp-dns.html
#   http://www.g10code.de/docs/pka-intro.de.pdf (German PDF)
set crypt_use_pka=yes

# Add OpenPGP header
# See: https://datatracker.ietf.org/doc/draft-josefsson-openpgp-mailnews-header/?include_text=1
my_hdr OpenPGP: url=http://domain.tld/pubkey.asc; id=12345678

When I try to open an e-mail, I got this message:

[-- Error: decryption failed: No secret key --]

Do you have any idea why the public key of the sender is not detected?

Thanks.