Install claws-mail-fetchinfo-plugin by entering the following commands in the terminal:
sudo apt update sudo apt install claws-mail-fetchinfo-plugin
Add X-FETCH headers plugin for Claws Mail
This plugin for the Claws Mail mailer enables adding useful extra headers to the received mails with information like the receiving account or the server the mail was downloaded from. These extra headers can be used for filtering and/or processing messages more appropriately.