Quick and easy! I have found that this solution is even better than it was before with the stationery feature in older versions of the Mail App. The original is left in the Templates folder so you can reuse it again and again. In the Templates folder, right click on the message you want to use as a template and click “Send again”. The message will open as an editable message, so you can tweak and personalize it before sending it.

Move your draft message to the Templates folder. Drag and drop the email draft you saved earlier to the Templates folder you just created.

Create a new email folder called “Templates”. You can call it whatever you want, but this will be the home for all of your template messages.

Close the draft and you will be prompted to save it. You can even add pictures and attachments as part of your template. Formatting (bold, colors, etc.) all work fine. You can populate the To, Cc, Bcc, Subject and Body of the email with whatever you need to be part of your template.

Apple pages templates format