Create a transport rule to bypass a Safe Attachments policy

  • 4 minutes

Sometimes it's useful to allow mail with attachments to flow without delay from internal senders or from trusted scanners, faxes, and smart hosts. An organization might decide that if the mail is from a trusted source, the attachments must be safe.

If an organization wants to implement such a policy, it can create a transport rule, also known as a mail flow rule, in the Exchange admin center. The purpose of this rule would be to bypass Safe Attachments scanning.

To create a transport rule that bypasses Safe Attachments scanning, complete the following steps:

  1. In the Microsoft 365 admin center, in the left-hand navigation pane, select Show all.

  2. In the left-hand navigation pane, under the Admin centers group, select Exchange.

  3. In the Exchange admin center (EAC), in the left-hand navigation pane, select Mail flow and then select Rules.

  4. On the Rules page, select +Add a rule on the menu bar. In the drop-down menu that appears, select Create a new rule. Doing so initiates the New transport rule wizard.

  5. In the Set rule conditions page, enter a name for your new rule.

  6. In the Apply this rule if section,select the first field. In the drop-down menu, select an option, such as The sender. Select the second field, and in its drop-down menu select is external/internal. In the Select sender location pane, select Inside the organization, and then select Save.

    Note

    You can choose from several options in each drop-down menu. For example, you can select other criteria, including senders, recipients, distribution group members, and attachment types.

  7. In the Do the following section, select the first field. In the drop-down menu, select an option, such as Modify the message properties. Select the second field, and in its drop-down menu select set a message header.

  8. Note the text that appears below the two fields: Set the message header Enter text to the value Enter text.

  9. Select the first instance of Enter text. In the message header pane that appears, enter X-MS-Exchange-Organization-SkipSafeAttachmentProcessing as the header name, and then select OK.

  10. Select the remaining *Enter text, and then type something, such as a space, and then choose OK.

    Note

    The system doesn't use this value, even though it requires a value for the rule to work.

  11. To save your settings, select Save.

Knowledge check

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Check your knowledge

1.

Contoso decided that when the mail its users receive is from a trusted source, any attachments are assumed to be safe. It also wants to allow mail with attachments to flow without delay from internal senders. What should Contoso do to implement this business requirement?