A plain text email is an email made only of text without any HTML coding. In the first years of the Internet emails were only text email.
Beside simplicity of design and low file sizes, the main advantage of plain text email is now the absence of rendering issue. The -poor- visual rendering is the same for all email clients and interfaces and all inboxes and devices can read a text email.
Main drawbacks of text emails are:
there are no images
there is no choice of fonts, colors or other text enhancements (bold, ital, etc.)
text layout is limited
the message is visually poor
links are written out as full URLs
email opening can’t be tracked (see below)
Often, emails which seem to be pure text are in fact HTML emails because they include a transparent 1X1 pixel bug within an HTML tag for opening tracking.
True text emails are commonly used as an alternative text version for now classic HTML emails. With multipart coding or process the text version is normally displayed if the device or email client can’t interpret and display HTML emails. It can also be used for recipients who have chosen to receive a text version.
Below, a false text email, it doesn’t use HTML coding to secure rendering but it includes a HTML pixel tag for measuring open rate.