NinjaOne Ticketing SMTP Microsoft 365 Troubleshooting “Error: Access denied, Your organization does not allow external forwarding”

Issue

Technicians receive rejection errors when attempting to configure the SMTP email for NinjaOne Ticketing. 

Remote server returned '550 5.7.520 Access denied, Your organization does not allow external forwarding. Please contact your administrator for further assistance. AS(7555)'

Environment

NinjaOne Ticketing

Cause

Your organization has disabled automatic external email forwarding in Microsoft 365 (Exchange Online) due to security policies.

Resolution

System administrators can modify the outbound spam policy to allow external forwarding.

Option 1: Modify the Outbound Spam Policy

1. Sign in to the Microsoft 365 Defender portal (https://security.microsoft.com/).
2. Go to Policies & rules > Threat policies.
3. Click Anti-spam policies.
4. Under Outbound spam filter policy, click Edit policy.
5. Scroll down to Automatic forwarding.
6. Change the setting from Automatic – System-Controlled to On – Forwarding is enabled, or On – Forwarding is enabled for select domains (depending on your needs).
7. Save the changes.

Option 2: Check Mail Flow Rules (Transport Rules)

If forwarding is still blocked, check for mail flow rules:

1. Go to Microsoft 365 Admin Center > Exchange Admin Center.
2. Navigate to Mail Flow > Rules.
3. Look for any rules that block forwarding and modify them accordingly.

Additional Resources

• NinjaOne Ticketing: SMTP Microsoft 365 Configuration
• Ticketing Resource Catalog