554 5.3.3 System not capable of selected features

Meaning

Selected features are not supported by the destination system.

Common causes

• Unsupported SMTP extension.
• Incompatible systems.

How to fix

1. Disable unsupported features.

Example bounce

554 5.3.3 System not capable of selected features

Related codes

• 554 5.7.1 Message rejected / Spam block
• 554 Transaction failed
• 550 5.4.1 Recipient address rejected: Access denied