While in Communications tab, click on New Message button:
The preview panel with open, with input fields needed for creating a new message.
First, choose an e-mail account connected to your Saasuma account that you would like to use as a sender. The account you choose will be shown as a sender's e-mail address to the recipient, without showing that it was sent using Saasuma.
In the next input field (TO) enter the recipient's e-mail address, and in the SUBJECT field enter the subject of your message.
Add the e-mail content in the largest field bellow.
When you have everything prepared for sending, click on the Send Message button in the bottom right corner.