HTML format, often termed "rich text" content, allows for the inclusion of various elements such as text, links, images, tables, and formatting like font styles and colors.

Plain text format, on the other hand, consists solely of text and links without any additional formatting, images, or tables.

Presently, the majority of users lean towards the HTML format for viewing content, often resulting in higher response rates. Nevertheless, some users still prefer plain text emails, particularly due to performance considerations related to their device or email interface. Additionally, individuals with visual impairments may favor plain text emails.

Both HTML and plain text emails can be created using any email builder. When sending an email crafted in both HTML and plain text formats, a multi-part message containing both versions is dispatched. The recipient's email interface determines which version to display, and they typically receive only one version, not both as seen during testing. To exclude the plain text version entirely, simply remove its content. Moreover, it's possible to override the default email interface preference for individual contacts by specifying a preferred email format before sending an email campaign.