Plain Text Editor
From LongJump Support Wiki
For Email Messages
When sending an email message as part of a campaign, include a plain text version along with the HTML version. Email recipients can set their email clients to only accept plain text email messages as a security option. In this case, HTML messages are not displayed, and only the plain text is displayed.
Plain text email messages do not include images or graphics, however, they can include a link to your website, where email recipients can experience your messaging in full HTML, with color, fonts and animation.
A plain text email message will contain text only, and is likely to be displayed in the Courier font.