Below are the steps to set up a mail flow rule to bypass Safe Attachments Processing.

1. Create a new mail flow rule in your Microsoft 365 Exchange Admin Center.
2. Give the rule a name, e.g. Bypass Safe Attachments.
3. Click More Options.
4. From the 'Apply this rule if…' drop-down, selectthe senders, followed by IP address is in any of these ranges or exactly matches. 
5. Enter our IP addresses. Please see IP Addresses for the most up-to-date list.
6. From the 'Do the following…' drop-down, select Modify the message properties... and then set a message header.
   
   • Click the first *Enter text... link and set the message header to:
     • X-MS-Exchange-Organization-SkipSafeAttachmentProcessing
   • Click the second *Enter text... link and set the value to1.
7. To finish, click Save.