Read signed e-mail as plain text
Supported on: At least Windows Server 2008 R2 or Windows 7
Registry
software\policies\microsoft\office\16.0\outlook\options\mail Value name: readsignedasplain
Enabled: readsignedasplain = 1
Disabled: readsignedasplain = 0
Description
This policy setting determines whether Outlook renders all digitally signed e-mail in plain text format for reading. Outlook can display e-mail messages and other items in three formats: plain text, Rich Text Format (RTF), and HTML. If you enable this policy setting, the "Read all standard mail in plain text" check box option is selected in the "E-mail Security" section of the Trust Center and users cannot change it. This option only changes the way e-mail messages are displayed; the original message is not converted to plain text format. If you disable or do not configure this policy setting, Outlook displays digitally signed e-mail messages in the format they were received in.