There are different techniques to display images in emails.
Depending on what method is used, certain email clients will
show images not until a security prompt is confirmed by the user.
Please choose one of the four methods that works best for your
users and conforms to your companies policy.
Images are referenced by an URL and loaded by the email client from a web server.
Images are part of the email as multipart attachments, and referenced from within the message body.
Images are part of the email as encoded inline data inside the message body.
Images will not be shown at all.