You can save any email as a template and then start composing new messages from this template (it doesn't work for replies all that well, unfortunately).
Save and Use a Message as a Template in Evolution
To save and use a message as a template in Evolution:
- Select New | Mail Message from the Evolution toolbar.
- Compose your template.
- Make sure you use a Subject: that helps you recognize the template later.
- Select File | Save Draft from the menu.
- Close the message composition window.
Now, to create a message from your newly created template:
- Go to the Drafts folder.
- Double-click the desired "template".
- Compose and send the message.
- Make sure you never select File | Save Draft from the menu. This would overwrite your message template.
- Go to the Trash folder.
- Click on the deleted message template with the right mouse button.
- Select Undelete from the menu.
This moves the message template back to the Drafts folder where you can use it like before.

