Suppression List

The suppression list contains email addresses that Relay will not send to. Addresses are added automatically when emails bounce or generate complaints, or manually by administrators. Suppression protects your sender reputation and ensures SES compliance.

How It Works

Before every email send, Relay checks all recipient addresses (to, cc, bcc) against the suppression list. Suppressed addresses are silently skipped — the email sends to remaining recipients without error.

If all recipients are suppressed, the send returns a 400 error indicating no valid recipients.

Automatic Suppression

Relay automatically suppresses addresses in two cases:

Event	Trigger	Suppression Reason
Hard bounce	SES reports a permanent delivery failure (invalid address, domain doesn't exist)	bounce
Complaint	Recipient marks the email as spam in their email client	complaint

Automatic suppression happens in real-time via SES webhook events. The address is suppressed within seconds of the bounce or complaint.

ℹ️Soft bounces (mailbox full, server temporarily unavailable) do not trigger suppression. SES retries soft bounces automatically.

Manual Suppression

To manually suppress an address:

1. Go to Suppressions in the left sidebar
2. Click Add Suppression
3. Enter the email address
4. Click Add

The address is immediately suppressed with reason manual.

When to Manually Suppress

• Client requests to stop receiving emails
• Known invalid addresses from a list import
• Addresses you know will bounce (e.g., former employees at a client)
• Compliance or legal hold requirements

Viewing the Suppression List

The Suppressions page shows all suppressed addresses with:

• Email address
• Reason — bounce, complaint, or manual
• Bounce type — For bounces: Permanent, Transient, etc.
• Source message — The message ID that triggered the suppression (for automatic entries)
• Date added

Removing a Suppression

Click the remove icon next to an address and confirm. The address is immediately eligible to receive emails again.

⚠️Only remove suppressions if you're confident the underlying issue is resolved. Sending to an address that previously bounced will bounce again and hurt your sender reputation.

Common valid reasons to remove a suppression:

• The recipient fixed their mailbox (was full, now has space)
• The bounce was a temporary DNS issue that's been resolved
• The complaint was accidental (recipient confirms they want emails)

Bulk Import

To import multiple suppressions at once:

1. Click Import
2. Paste email addresses, one per line (maximum 500 per import)
3. Click Import

All imported addresses are suppressed with reason manual.

Use bulk import when:

• Onboarding a new client with a known do-not-email list
• Migrating suppression lists from another email provider
• Proactively blocking known problematic addresses

Bulk Export

Click Export to download the entire suppression list as a CSV file. The export includes all fields: email, reason, bounce type, source message ID, and date.

Use exports for:

• Auditing and compliance reporting
• Backing up the suppression list before changes
• Cross-referencing with other systems

API Reference

Manage suppressions via the API with a key that has the manage-suppressions scope:

Method	Endpoint	Description
GET	/api/suppressions	List all suppressions
POST	/api/suppressions	Suppress an address
DELETE	/api/suppressions/{email}	Remove a suppression
GET	/api/suppressions/export	Export as CSV
POST	/api/suppressions/import	Bulk import (max 500)