Details
This policy setting allows you to control how plain text messages are formatted when they
are sent from Outlook. If you enable this policy setting, text is automatically wrapped in
Internet e-mail messages and attachments are encoded in UUENCODE format. If you
disable this policy setting, Outlook uses the standard MIME format to encode attachments
in plain text Outlook messages. Users will not be able to change this configuration. If you do
not configure this policy setting, the behavior is the equivalent of setting the policy to
Disabled, but users can modify plain text options in Outlook when required by clicking
Tools, clicking Options, clicking the Mail Format tab, clicking Internet Format, and changing
the values under ‘Plain text options’. The recommended state for this setting is- Disabled.
*Rationale*
If outgoing mail is formatted in certain ways, for example if attachments are encoded in
UUENCODE format, attackers might manipulate the messages for their own purposes. If
UUENCODE formatting is used, an attacker could manipulate the encoded attachment to
bypass content filtering software. By default, Outlook 2010 automatically wraps plain text
messages at 76 characters and uses the standard MIME format to encode attachments in
plain text messages. However, these settings can be altered to allow e-mail to be read in
plain text e-mail programs that use a non-standard line length or that cannot process MIME
attachments.
Solution
To implement the recommended configuration state, set the following Group Policy setting
to Disabled.
User ConfigurationAdministrative TemplatesMicrosoft Outlook 2010Outlook
OptionsMail FormatInternet FormattingPlain text options- Automatically wrap text
at
Impact-If this setting is not configured, users can modify plain text options in Outlook 2010 when
required by clicking Tools, clicking Options, clicking the Mail Format tab, clicking Internet
Format, and changing the values under Plain text options. If you enable this policy setting,
text is automatically wrapped in Internet e-mail messages and attachments are encoded in
UUENCODE format.
Supportive Information
The following resource is also helpful.
This security hardening control applies to the following category of controls within NIST 800-53: Configuration Management.This control applies to the following type of system Windows.