Occasionally the wrong message is marked as deleted
When trashing a large number of conversations in quick succession, Geary will occasionally flag the a message in the conversation before the deleted conversation as also being deleted. This will not actually delete the message, it will just no longer be show in the conversation. Restarting Geary will restore the missing message.
This bug is difficult to reproduce and hence fix. If you encounter this problem, please run Geary from the command line using the following commands:
geary -d --log-replay-queue --log-network | tee geary.txt
or for Flatpak installations:
flatpak run org.gnome.Geary -d --log-replay-queue --log-network | tee geary.txt
When the problem occurs, please mention it here forward the log file to the developers.