OfflineIMAP: Periodically fetch emails with systemd's timers

When I switched from Gmail web interface to Mutt+OfflineIMAP, I used the autorefresh feature of OfflineIMAP.

But after only few hours of run, the process consumes more than a gigabyte of memory while it consumes only ~300MB on the first fetch.

A lot of people prefer to use a cronjob to replace autorefresh and execute the process only once on each fetch, but since I'm using systemd I can directly use a timer to do the same thing.

First of all, we need to write a little service for offlineimap, named offlineimap.service:

[Unit]
Description=OfflineIMAP Service
After=network.target

[Service]
Type=simple
ExecStart=/usr/bin/offlineimap

Note: If you use gpg-agent to retrieve your passwords, add this line in the Service section: EnvironmentFile=/path/to/your/.gpg-agent-info

Note 2: If you use a systemd service to start gpg-agent¹, add the following line in the Unit section: Requires=gpg-agent.service

The timer is shorter and named offlineimap.timer:

[Timer]
OnUnitInactiveSec=120s
Unit=offlineimap.service

Offlineimap will run 2 minutes after each deactivation of the unit (OnUnitInactiveSec) with this timer.

Note: You can write another timer with a different interval if you have slow connections while traveling.

After adding these files you can start the timer with systemctl --user start offlineimap.timer.

You must start the service for the first run after starting the timer with systemctl --user start offlineimap.service since the timer activates the service after the last deactivation.

General Note: Please be careful when you shutdown your computer. If offlineimap is running, there is a high probability that one of the databases become corrupted.

Enjoy!