How do I troubleshoot block bounces?

Troubleshooting block bounces requires systematic investigation:

Step 1: Read the full error

Extract exact message text. Note any reference URLs or codes. Identify which provider blocked you.

Step 2: Check blocklists

Query major blocklists (Spamhaus, Barracuda, etc.). Check both IP and domain. Request removal if listed.

Step 3: Verify authentication

Test SPF, DKIM, DMARC alignment. Ensure all sending IPs are authorized. Check for configuration errors.

Step 4: Review content

Scan for spam trigger patterns. Check URLs against blocklists. Review recent campaign content.

Step 5: Check reputation tools

Google Postmaster Tools. Microsoft SNDS. Provider-specific dashboards.

Step 6: Follow remediation

Many block messages include remediation URLs. Follow provider-specific processes.

Block bounces are symptoms. Find and treat the underlying disease.