Flash is a popular program developed by Macromedia. It is used to create graphics-based animation with full-screen navigation interfaces, graphic illustrations and simple interactivity in a file format that is small enough to stream across a normal modem connection. The software is extremely common on the internet and over 97% of internet users already have have Flash installed.

Using Flash in email marketing can increase the effectiveness by 4 to 5 times over other forms of email promotion.