This thread aspires to be a tutorial on how to send Chatmails using Neomutt (on Debian-based distros, but should be helpful even if you aren’t running any form of Linux). It does not currently work.
By default, Chatmail servers let anyone set up a free account, but they reject any mail that does not meet their specific formatting requirements. It is fairly easy to set up a conventional mail client that will receive Chatmails, but making one send Chatmail in the correct format is harder.
First, you must use Autocrypt. Many e-mail clients do not yet implement the Autocrypt standard (list, rather outdated).
I’ve chosen to use Neomutt, because it in the Debian stable package database and is highly configurable. Unfortunately, this means it has a steepish learning curve and needs configuration. The documentation is also pretty terrible. You can use the mutt-wizard package to semiautomate some of the setup.
First, install Neomutt and dependencies. On Debian-based systems:
#Make sure your system is up-to date
sudo apt update && sudo apt upgrade
#type your password
#confirm
#install Neomutt and its dependencies
sudo apt install neomutt
If you run neomutt -v, you will notice that it has “-autocrypt” as a compile option. We need Autocrypt, and alas, we can’t have it unless we recompile Neomutt with the “autocrypt” compile-time option enabled.
If you do not already have them, you will need to install the package-compilation tools.
#to install any missing package-compilation tools
sudo apt-get install build-essential fakeroot dpkg-dev
#to install build any dependencies
sudo apt-get build-dep neomutt
You normally just download built binaries from the Debian package database, but to recompile the package obviously you need the source code. If you haven’t done it already, you need to configure Debian to download source code. The details of your configuration may vary.
Look through /etc/apt to find your sources file if needed.
#As superuser, open your sources file in a text editor
#For instance, if your text editor is vi:
sudo vi /etc/apt/sources.list
This should open a file that, if it is the old configuration says something like
deb http://deb.debian.org/debian bookworm main contrib
deb http://security.debian.org/ bookworm-security main contrib
deb http://deb.debian.org/debian bookworm-backports main
In which case, you need to add something that says
deb-src http://deb.debian.org/debian bookworm main contrib
deb-src http://security.debian.org/ bookworm-security main contrib
deb-src http://deb.debian.org/debian bookworm-backports main
Alternately, if you have the new deb822 configuration (a from-scratch install of >Debian13/Trixie, or you have run apt modernize-sources), your sources file will look somewhat like this:
Types: deb deb-src
URIs: http://deb.debian.org/debian
Suites: trixie trixie-updates
Components: main non-free-firmware
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg
Make sure that the first line contains “deb-src”; if it is absent, add it.
This tells Debian whence to download source code.
Now, at the terminal,
apt-cache showsrc neomutt
It should give you about 20 lines of information on one or more versions of the Neomutt package. If it tells you it can’t find sources, go back and fix your apt sources config file.
Next,
#make a directory to hold your source code
mkdir ~/Documents/neomutt_setup/
#Change Directory into it.
cd ~/Documents/neomutt_setup/
It doesn’t really matter where you make your directory or what you call it.
#Download the neomutt source code
sudo apt-get source neomutt
#Go into subdirectory
cd src
Now tell the package management system about the source. Type dpkg-source -x neomutt_, then press tab repeatedly to autocomplete. Pick the package version you want. You will wind up with a command similar to dpkg-source -x neomutt_20250510+dfsg-2~bpo12+1.dsc. Run it.
Type ls to see the new directory. Descend into the new directory using a command similar to cd neomutt-20250510+dfsg/
#Set compile flag
export CFLAGS="--autocrypt"
#Compile
sudo dpkg-buildpackage -rfakeroot -b
#This will take a while
When it has compiled, again type ls and get the name of the .deb file, then run something like
#Install the newly-compiled package
sudo dpkg -i neomutt_20250510+dfsg-2~bpo12+1_arm64.deb
Now run neomutt -v again. You will see it now has “+autocrypt” as a compile-time option.
In your muttrc configuration file (which may well be in ~/.config/mutt), add these lines:
set autocrypt
#accept defaults
bind index ^A autocrypt-acct-menu
# bind ctrl-a to open Autocrypt address menu
Export your Deltachat config and configure Neomutt.
And now the problem: it doesn’t work. I can’t access the Autocrypt address menu, so I can’t make any account use Autocrypt.
If anyone has advice on what is wrong with my Neomutt config, please let me know!