Read All Mail in Plain Text Only in Outlook
To have all emails rendered and displayed in plain text in Outlook 2019, 2016, 2013, and 2010:
Read an Individual Message Using Rich HTML Formatting
When Outlook is configured to show messages in plain text only, you can selectively choose which messages to read in HTML format.
Read All Mail in Plain Text Only in Outlook 2007
To make Outlook 2007 render all messages in secure plain text:
Read All Mail in Plain Text Only in Outlook 2003
To have Outlook 2003 display all messages in secure plain text:
Why Read Emails in Plain Text?
Email messages and newsletters with rich HTML formatting contain elements that may come with risks. These risky HTML messages may contain viruses or slow down your computer. These messages may also pose a privacy risk by contacting remote servers when you open the message. Make reading email in Outlook more secure and protect your privacy by reading messages in plain text only.