User is not local. This means that both your address and recipients address are not locally facilitated by the server, a relay can be interrupted.
Cause
- Used as a strategy for spam prevention.
- Sender and recipient address are not locally hosted by the server, a relay can be interrupted.
Fixes
Step 1: Contact NET
Contact NET Support and ask them to allow you as a certified sender.
Step 2: Email Authentication
Ensure proper email authentication.
Step 3: SMTP Relays
Allow SMTP relays.