Enabling this feature allows you to access stored templates from the authoring page.
1. Navigate from the home menu to Manage.
2. Go to Lists.
3. Go to List Settings.
4. Navigate to the message composition section.
5. Select Yes for Enable template selection within author page?
6. Scroll to the bottom of the page and click Commit Changes.
Now that you've enabled this option, you will see the below drop-down menu on the authoring page (Authoring > New Message). The option to select any of your saved templates will appear just above the WYSIWYG editor: