PeopleTools 8.4x added an option in the PeopleCode function
SendMail() for specifying the content-type. In PeopleBooks, what is immediately highlighted is the ability to format your emails using HTML by setting the content-type to text/html. What probably isn’t well known is that it is also possible to set the content-type to other MIME types such as multipart/related.
text/html alone will allow you to format the text of your message. But if you need to display an image such as a logo, <img> tags inside your html will need to link to images stored in a web server somewhere. Sometimes, this is not ideal. With multipart/related, you can embed images in your email messages.