Microsoft Outlook 2016 Security Technical Implementation Guide

The Microsoft Outlook 2016 Security Technical Implementation Guide (V2 R4) has 64 STIG checks. New to STIG checklists? Read What is a STIG checklist?, CKL vs CKLB, and STIG vs SCAP benchmark.

Find STIG checks

64STIG checks

Search filters this STIG's checks locally. Separate terms must all match (use quotes for an exact phrase). A search you ran on the Search page carries over here.

Severity

Version

V2 · R4

CurrentPublished Mon Jan 05 2026

Outlook Rich Text options must be set for converting to plain text format.

Microsoft Outlook 2016 Security Technical Implementation Guide

Assessment Title

Rule Text

Outlook Rich Text options must be set for converting to plain text format.

Description

Discussion Text

Outlook automatically converts Rich Text Format (RTF) messages that are sent over the internet to HTML format, so that the message formatting is maintained and attachments are received.
This setting controls how Outlook sends RTF messages to internet recipients.

New to STIG checklists? Read What is a STIG checklist? and CKL vs CKLB.

Objective

V-251867

Rule

SV-251867r961863_rule

Severity

medium

Rule Version

DTOO344

Documentable

false

IA Controls

NIST SP 800-53

Rev 5

Assessment Procedure

Check Text

Verify the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Outlook Options >> Mail Format >> Internet Formatting "Outlook Rich Text options" is "Enabled: Convert to Plain Text format".

Procedure: Use the Windows Registry Editor to navigate to the following key: 

HKCU\Software\Policies\Microsoft\Office\16.0\outlook\options\mail

Criteria: If the value Message RTF Format is REG_DWORD = 1, this is not a finding.

Implementation Procedure

Fix Text

Set the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Outlook Options >> Mail Format >> Internet Formatting "Outlook Rich Text options" to "Enabled: Convert to Plain Text format".

STIG check 62 of 64 in the Microsoft Outlook 2016 STIG checklist

← Previous · V-251866The default message format must be set to use Plain Text.Next · V-251872 →Text in Outlook that represents internet and network paths must not be automatically turned into hyperlinks.