McAfee Security for Microsoft Exchange 8.6.0

Configure MIME mail settings

Configure settings in a policy to identify encoded MIME messages and take necessary actions.

Multipurpose Internet Mail Extensions (MIME) is a communications standard that enables the transfer of non-ASCII formats over protocols (such as SMTP) that supports only 7-bit ASCII characters.

MIME defines different ways of encoding the non-ASCII formats so that they can be represented using characters in the 7-bit ASCII character set.

Task
1 From Policy Manager, select a submenu item that has the filter.
The policy page for the submenu item appears.
2 Click Master policy or any subpolicy you want to configure, then click List All Scanners tab.
3 Click MIME Mail Settings.
If you add a new filter to the policy, you can specify a time slot when to enable the filter, using What time would you like this to apply drop-down list.
4 In Options, select <create new set of options>.
The Mail Settings page appears.
5 In Instance name, type a unique name for the MIME email filter setting instance. This field is mandatory.
6 In Options tab, type a Prefix to message subject.
a In Preferred re-encoding of attachments in a MIME message, select a re-encoding method that is used when re-encoding attachments in MIME messages from the options available.
b In Preferred re-encoding of modified subject headers, select a re-encoding method that is used when re-encoding the subject headers in the MIME messages from the options available.
c In If re-encoding a subject header fails, select one of these options:
Treat as an error — If the MIME message is bounced.
Fallback to UTF-8 — If the MIME message is encoded into UTF-8.
7 In Advanced tab, select one of these encoding methods to use while encoding the text part of an email message:
Quoted-Printable, which is best suited for messages that mainly contain ASCII characters, but also contains some byte values outside that range.
Base64, which has a fixed overhead and is best suited for non-text data, and for messages that do not have a lot of ASCII text.
8-Bit, which is best suited for use with SMTP servers that support the 8BIT MIME transport SMTP extension.
You can perform step 6b only if you select Re-encode using the original encoding scheme or Re-encode using the following character set from Preferred re-encoding of modified subject headers.
a Select or deselect Do not encode if text is 7-bit as required. d In Header corruption in a MIME message, select the required option.
b In Default decode character set, select a character set that should be used for decoding when one is not specified by the MIME headers. e In NULL characters in the headers of a MIME message, select the required option.
c In Maximum number of MIME parts, specify the maximum number of MIME parts that can be contained in a MIME message. Default value is 10000 MIME parts. f In Quoted-printable characters encoding in a MIME message, select the required option.
8 In MIME Types tab, specify which MIME types should be treated as text attachments and which, as binary attachments.
Click Add to add the MIME types to the list or Delete to delete a MIME type from a list. Duplicate entries are not allowed.
9 In Character Sets tab, select Character set and Alternatives, deselect the Fixed checkbox, and click Add to specify an alternative character set mapping to the one specified in the MIME message.
Click Edit to edit character mappings, Delete to delete character mappings and click Save to apply any changes you have made to the character mappings.

The Save option is available only when you click Edit.

10 Click Save.
11 In Alert selection, you can select which alert to use when a MIME type is blocked. You can use:
Create — To create a new alert message for this policy.
View/Hide — To display or hide the alert text. If the text is hidden, clicking this link displays it. If the text is displayed, clicking this link hides it.
12 In Incomplete message actions, click Edit to specify the filter actions that must be taken when a partial MIME or external MIME type is encountered.
13 Click Save to return to the policy page.
14 Click Apply to configure these settings to a policy.