What is Relay and how does it protect your inbox?
How Relay filters spam and threats before they reach your mail server.
Relay
Relay
Setting up inbound MX relay protection, per-address settings, delivery, and troubleshooting.
Setting up Relay for your domain
Step-by-step: MX records, SMTP destination, and testing your setup.
Configuring per-address relay settings
Custom spam thresholds and configuration for each protected address.
Understanding relay delivery failures and retries
What happens when SMTP forwarding fails, how the retry queue works, and how to fix common issues.
Relay token configuration - prevent bypass and enforce on your server
Why the X-Cleanbox-Validation token matters, where to find it, and step-by-step configuration for Exim, Postfix, and Dovecot.
Relay spam symbols and virus scanning
How relay spam symbol rules work, what each authentication and content symbol means, and how ClamAV virus scanning protects your mail server.
How ClamAV virus scanning protects your relay addresses
How ClamAV works in Cleanbox Relay, what it detects, where it sits in the processing chain, and what happens when a virus is found.
Why do I see "via srs.cleanbox.to" in my email?
Some email clients show a "via srs.cleanbox.to" label on messages delivered through Relay. This is expected behavior caused by SRS envelope rewriting.
How relay email processing differs from aliases
The technical differences between how Cleanbox handles relay addresses and alias addresses.
Choosing between aliases and relay for your setup
A practical guide to help you decide whether aliases, relay, or both are the right fit for your email setup.
Testing and verifying your relay delivery
How to test your relay setup, verify that email flows correctly, and troubleshoot common delivery issues.
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