Definition
Blocked contacts are subscribers who have been suppressed from your active email list — they will not receive any future campaigns. Blocking occurs automatically in response to hard bounces, spam complaints, unsubscribe requests, or manual suppression by the sender.
Maintaining a comprehensive block list is essential for deliverability and compliance. Sending to blocked contacts can result in issuer-level blocks from mailbox providers and violations of CAN-SPAM, CASL, and GDPR. Most ESPs maintain automatic suppression lists, but understanding what gets blocked and why is critical for list management.
Reasons Contacts Get Blocked
| Reason | Trigger | Duration |
|---|---|---|
| Hard bounce | Invalid or non-existent email | Permanent |
| Spam complaint | Recipient marked as spam | Permanent |
| Unsubscribe | Recipient opted out | Permanent (by law) |
| Soft bounce threshold | Multiple soft bounces over time | Varies by ESP |
| Manual suppression | Sender decision | Until reinstated |
| Abuse complaint | Feedback loop notification | Permanent |
Best Practices
- Never remove contacts from a suppression list to send to them again
- Review blocked contact reports regularly to understand why contacts are lost
- Investigate spikes in blocking — they indicate list quality or sending issues
- Ensure unsubscribe processing is immediate per legal requirements
- Maintain separate suppression lists for different reasons (bounce, complaint, unsubscribe)
- Use suppression lists at the ESP level and maintain your own copy for portability
Related Glossary Terms
Email Bounce Handling Automation
Email bounce handling automation uses automated workflows to classify, score, and suppress bounced addresses, protecting sender reputation through progressive suppression rules and real-time monitoring.
Email Consent Renewal
Consent renewal campaigns restore permission to email subscribers whose consent has expired under GDPR regulations, typically achieving 10-30% renewal rates.
Email Delivery Failure
Reasons, diagnostics, and solutions for emails that fail to reach the recipient's inbox, including hard bounces, soft bounces, and blocks.
Delivery Rate
Email delivery rate is the percentage of sent emails that are accepted by the recipient's mail server, distinct from inbox placement rate which measures how many reach the inbox.
Email Dormant Subscriber
A dormant subscriber has not engaged with emails for a defined inactivity period, typically 90-365 days depending on industry. Dormancy classification triggers suppression and re-engagement activities.
Email Engagement Recapture
Email engagement recapture re-engages lapsed subscribers through targeted campaigns at defined inactivity intervals, with structured sunset policies for non-responsive contacts.
Frequently Asked Questions
Only if the contact explicitly re-subscribes with full consent. Former subscribers who re-subscribe should be treated as new contacts and re-onboarded through your standard sign-up process. You should never re-add someone who unsubscribed or bounce-suppressed without their explicit action.
Permanently for unsubscribes, hard bounces, and spam complaints. Soft bounces may be aged out after a defined period. Check your ESP's policy and ensure your suppression list is preserved even if you migrate to a different ESP.