The list of different types of email templates that can be created in Salesforce is given below :
Text : All the users in the organization are allowed to create or change these templates.
HTML with letterhead : Only administrators and users with the “Edit HTML Templates” permissions are able to create these templates based on a letterhead. The look and feel of your HTML email templates are defined by the letterheads. It can inherit the logo, text, and color settings from a letterhead.
Custom HTML : It is an extension of HTML with a letterhead. Administrators and users having “Edit HTML Templates” permissions can create custom HTML templates without using the letterhead. You must have knowledge about HTML or get the HTML code to insert it into your email template.
Visualforce : Administrators and developers are allowed to create these templates by using Visualforce. Visualforce templates provide advanced functionalities like merging with a recipient’s data, where the content of a template can have data from multiple records.
