Install sylpheed-plugins by entering the following commands in the terminal:
sudo apt update sudo apt install sylpheed-plugins
Description:
Loadable modules for extending Sylpheed features
This package comprises all loadable plugins which are included with Sylpheed sources. Plugins extend Sylpheed by providing new features and/or capabilities not present in core application. . Currently only the unique existing plugin is included: Attachment Tool: a plugin for dealing with attachments in messages.
Homepage: http://sylpheed.sraoss.jp/en/
Version: 3.5.1-1ubuntu3
Section: universe/mail