Microsoft 365’s spoof intelligence feature can be used to remove some errors and messaging in Outlook e.g. the “via sendgrid.net” that appears after a sender email.
How to remove the 'via sendgrid.net' tag from email in Outlook
1. Go to the Microsoft 365 Security Portal
2. Navigate to Email & Collaboration > Policies & Rules > Threat Policies > Tenant Allow/Block List
3. Click on the Spoofing tab
4. Click Add
5. Configure the Add new domain pairs window
Paste the following into the Add domain pairs with wildcards field
Set Spoof Type to External
Set Action to Allow
6. Click Add to save your changes
Note on wildcards
Following the guide above will allow emails sent from usecure's IPs to spoof any sender domain. If you don’t feel comfortable using a wildcard in this allow list, you can add entries for each domain you wish to use for simulated phishing emails or system notifications.