SendTools is a sophisticated extension designed for the Mozilla email client, offering users the ability to schedule emails for specific send times. This feature streamlines communication management by enabling emails to be sent at optimal times without the need for active user presence. The extension seamlessly integrates with the email client, introducing new folders named "later" and "scheduled" to temporarily store messages before their designated send time.

Technically, SendTools enhances the email client's functionality by incorporating a scheduling control into the writing window. This user-friendly control, positioned in the upper right corner, allows users to precisely set the sending time for emails. Activating the scheduling feature is as simple as checking a designated checkbox, and the intuitive interface enables users to adjust the send time with ease by clicking on the control elements.