How to use Templates in Gmail

When composing an email, you can save the draft as a template to use in the future.

Click on the 3 vertical . in the bottom right of the New Message box - Click "Templates" - Click "Save draft as template".

Next time you would like to compose a similar email you can choose that saved template from the "Insert Template" section.

Make sure to delete your email signature before saving your template or it will insert 2 signatures when you use the template.