Prevent users from sending attachments in Gmail

Need to prevent users from sending attachments to internal and also to external users and  how to create an attachment compliance rule.

• Admin console 

1. Go to the Compliance page.
2. Next to Attachment compliance, click on Configure.
3. Add a name to the rule.
4. Select the email messages to affect.
5. Select the file types you need to affect.
6. Under Attachments, click on Remove attachments from message.
7. Click on Save.