S/MIME signencrypt messages created with epg enabled are readable by gnus-article-mode and other emacs modes, but not anything else. Signed messages are fine. Encrypted-only (e.g., by setting "smime" to combined in mml-signencrypt-sytle-alist, which is not supported) is also fine. For example, the p7m attachment from an EPA enabled signencrypt message will decrypt, but resulting multipart won't verify with Outlook or gpgsm, but will verify with OpenSSL: ``` ~/Documents/projects/scratch/smime > gpgsm -d emacs.p7m > emacs.mime gpgsm: encrypted to rsa2048 key 28AB1F8A641EF8784309B496484C16A6C5F741A0 ~/Documents/projects/scratch/smime > gpgsm --debug 1 --verify emacs.mime gpgsm: reading options from '/Users/tmiller/.gnupg/gpgsm.conf' gpgsm: reading options from '[cmdline]' gpgsm: enabled debug flags: x509 gpgsm: enabled compatibility flags: gpgsm: ksba_cms_parse failed: End of file secmem usage: 0/16384 bytes in 0 blocks ~/Documents/projects/scratch/smime > openssl smime -verify < emacs.mime Content-Type: text/plain lsakdjfhlaskjdhflaksdjhflkasdjhflkajsdhflkajshdflkjashd alksdjuhflkasjdhflkasjdhflkasdjhflkasjdhflkasjdhflkasjdhf -- -- T Verification successful ``` If I configure S/MIME to use OpenSSL, signencrypt messages work just fine. A sample decrypted MIME parts attached with the signing cert if you need it. -- T In GNU Emacs 29.0.60 (build 1, x86_64-apple-darwin20.6.0, NS appkit-2202.70 Version 11.7.2 (Build 20G1020)) of 2023-03-10 built on MM273467-PC Windowing system distributor 'Apple', version 10.3.2022 System Description: macOS 11.7.6 Configured using: 'configure --disable-dependency-tracking --disable-silent-rules --enable-locallisppath=/usr/local/share/emacs/site-lisp --infodir=/usr/local/Cellar/emacs-plus@29/29.0.60/share/info/emacs --prefix=/usr/local/Cellar/emacs-plus@29/29.0.60 --with-xml2 --with-gnutls --with-native-compilation --without-compress-install --without-dbus --without-imagemagick --with-modules --with-rsvg --with-ns --disable-ns-self-contained 'CFLAGS=-Os -w -pipe -march=nehalem -mmacosx-version-min=11 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk -DFD_SETSIZE=10000 -DDARWIN_UNLIMITED_SELECT' 'CPPFLAGS=-I/usr/local/opt/zlib/include -I/usr/local/opt/jpeg/include -I/usr/local/opt/icu4c/include -I/usr/local/opt/openssl@1.1/include -F/usr/local/Frameworks -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk' 'LDFLAGS=-L/usr/local/opt/zlib/lib -L/usr/local/opt/jpeg/lib -L/usr/local/opt/icu4c/lib -L/usr/local/opt/openssl@1.1/lib -L/usr/local/lib -F/usr/local/Frameworks -Wl,-headerpad_max_install_names -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk'' Configured features: ACL GIF GLIB GMP GNUTLS JPEG JSON LCMS2 LIBXML2 MODULES NATIVE_COMP NOTIFY KQUEUE NS PDUMPER PNG RSVG SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP XIM ZLIB Important settings: value of $LANG: en_US.UTF-8 locale-coding-system: utf-8-unix Major mode: ELisp/l Minor modes in effect: shell-dirtrack-mode: t mu4e-modeline-mode: t format-all-mode: t global-hl-todo-mode: t hl-todo-mode: t corfu-popupinfo-mode: t global-corfu-mode: t corfu-mode: t marginalia-mode: t vertico-mouse-mode: t vertico-mode: t override-global-mode: t global-display-line-numbers-mode: t display-line-numbers-mode: t electric-pair-mode: t tooltip-mode: t global-eldoc-mode: t eldoc-mode: t show-paren-mode: t electric-layout-mode: t electric-indent-mode: t mouse-wheel-mode: t file-name-shadow-mode: t global-font-lock-mode: t font-lock-mode: t blink-cursor-mode: t line-number-mode: t global-visual-line-mode: t visual-line-mode: t indent-tabs-mode: t transient-mark-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t Load-path shadows: None found. 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format env code-pages mule custom widget keymap hashtable-print-readable backquote threads kqueue cocoa ns lcms2 multi-tty make-network-process native-compile emacs) Memory information: ((conses 16 712600 56314) (symbols 48 63261 3) (strings 32 262495 34299) (string-bytes 1 7453545) (vectors 16 72471) (vector-slots 8 1796940 116594) (floats 8 566 287) (intervals 56 16609 656) (buffers 984 33))