maildir_commander

maildir commander is a wrapper arond maildir-utils to make it more versatile. mu server is already state-less; however, it cannot be used by more than one client at a time. maildir_commander runs one instance of mu server in the background and make it an always-on daemon, so mu4e, command-line client and future web client can share the same underlying mu server instance through maildir_commander.

dependency

• mu 1.4+
• erlang OTP 21+
• socat, which is used to re-export the mu server compatible interface
• inotify-tools, for watching the Maildir for new mails

the server

maildir_commander can be used as a dependancy of a larger application or a stand-alone application. In the stand-aline mode, just run the release. It will run mu server in the background and communicate with it through a port. All functionalities of mu server are exported as erlang APIs via the mc_mu_api module.

The mu server will be ran on demand. If theere is nothing to do for some time (60 seconds by default) the mu server will be shut dowm to save memory. The on/off of mu server is automatic and user does not need to care about it except some small startup latency every once in a while.

the local socket

maildir_commander will also listen on a Unix domain socket $HOME/.mc_server_sock. The socket once connected, behave exactly like mu server. All commands are passed through to the shared mu server instance, with the only exception of the cmd:quit command, which is locally handled. so:

$ socat UNIX-CONNECT:$HOME/.mc_server_sock -

behave exactly like mu server, except now you can run multiple instances. I have a shell script in scripts/mc that can be a drop in repleacement of mu (now only mc server is supported, in the future I plan to re-implement more mu client side sub-commands). If you run maildir_commander as a daemon, mu will not work. To continue use mu4e, you would have to configure mu4e to use mc as the alternative mu binary.

the watcher

maildir_commander also has a watcher that watchs the Maildir for new mails and add to the mu database automatically. Given that maildir_commander always do a full index on startup, there is little reason to run indexing yourself anymore.

The watcher will also move new mails to the cur dir as per maildir standard. Therefore, you must ensure that the IMAP server is not getting in its way. If you are using exim, please make sure the local delivery is done via maildir_home, not with a IMAP specific LDA such as dovecot_delivery. Also please turn off the auto movement of new mails in your IMAP server. In dovecot, it is controlled in /etc/dovecot/conf.d/10-mail.conf with a line as:

maildir_empty_new = no

the archiver

maildir_commander contains an email archiver that scan your inbox and archive emailto .Archive maildir, based on the following rules:

• Mails are grouped into conversations first. Conversation that have emails within 30 days will be left alone. For all other conversations:
• If a conversation contains emails from me (as defined by the my_addresses configuration key), archive the whole conversation, will all attachments stripped off to save diskspace
• If the conversation has nothing to do with me, delete the whole conversation

To run the archiver, you just run mc archive. Most likely you have it in a nightly cronjob. Mails archived will still be searchable, just not in the inbox anymore. Right now the rules are not tunable, or rather, it is tuned to suit my need. My goal is to keep my inbox at constant size with minimal manual intervention.

Future works

maildir_commander is meant to be the lower layer of more sofisticated MUAs such as a web client, an IMAP client, etc, so they can run along side with the command line client and mu4e. In most cases you want to install LIV, which is a full webmail client based on Phoenix LiveView.