How to Use the Email Suppression List

This guide explains how to manage your email suppression list to maintain good sender reputation and comply with email best practices.

Overview

The suppression list prevents you from sending emails to addresses that have:

• Hard bounced (invalid or non-existent email addresses)
• Soft bounced (temporary delivery failures)
• Complained (marked your email as spam)
• Unsubscribed (opted out of emails)

Emails on the suppression list are automatically excluded from all campaigns.

Why Use a Suppression List?

Maintain Sender Reputation

• Sending to invalid addresses hurts your sender reputation
• High bounce rates can get your sending domain blocked
• ISPs monitor bounce and complaint rates

Compliance

• Required by email service providers (AWS SES, etc.)
• Helps comply with anti-spam regulations
• Protects your sending domain from being blacklisted

Cost Efficiency

• Avoids wasting sends on invalid addresses
• Reduces processing costs
• Focuses on engaged recipients

Accessing the Suppression List

1. Go to Email Marketing in the main navigation
2. Click on the Suppression List tab
3. You'll see:
   • Statistics cards showing totals by reason
   • Filter options
   • The suppression list table

Understanding the Statistics

At the top of the page, you'll see four stat cards:

• Total Suppressed: All emails in your suppression list
• Hard Bounces: Invalid or non-existent email addresses
• Complaints: Recipients who marked your email as spam
• Unsubscribes: Recipients who opted out

Viewing Suppressed Emails

The Suppression List Table

The table shows:

• Email Hash: Privacy-protected hash of the email address (first 12 characters)
• Reason: Why the email was suppressed (hard_bounce, complaint, unsubscribe, soft_bounce)
• Date Added: When the email was added to the suppression list
• Actions: Remove button (if you need to unsuppress an email)

Filtering the List

1. Use the Filter by reason dropdown at the top
2. Select a specific reason:
   • All (default)
   • Hard Bounce
   • Soft Bounce
   • Complaint
   • Unsubscribe
3. The table updates to show only matching records

Pagination

• The list is paginated for performance
• Use the pagination controls at the bottom to navigate
• Adjust items per page if needed

Adding Emails Manually

When to Add Manually

• Importing a list from another email service (like Mailchimp)
• Adding known invalid addresses
• Blocking specific addresses proactively

How to Add

1. Click the Add Email button
2. Enter the email address
3. Select the reason:
   • Hard Bounce: Invalid or non-existent address
   • Soft Bounce: Temporary delivery failure
   • Complaint: Spam complaint
   • Unsubscribe: Opt-out request
4. Click Add to Suppression List
5. The email is immediately added and will be excluded from future campaigns

Importing a Suppression List

Import from Mailchimp

If you're migrating from Mailchimp, you can import their "Cleaned Contacts" export:

1. Click Import List button
2. In Mailchimp:
   • Go to Audience → All contacts
   • Click "Export audience"
   • Select "Cleaned contacts" export
   • Download the CSV file
3. Back in TrustMinder:
   • Click Choose File and select your Mailchimp CSV
   • The system automatically detects Mailchimp format
   • Click Import
4. Review the import summary:
   • Total rows processed
   • Successfully imported
   • Skipped (duplicates or invalid)
   • Errors (if any)

Import Custom CSV

You can also import a custom CSV file:

Required CSV Format:

Email Address,Reason user@example.com,hard_bounce another@example.com,complaint

Supported Reasons:

• hard_bounce or hard bounce
• soft_bounce or soft bounce
• complaint or abuse complaint
• unsubscribe or unsubscribed

Steps:

1. Click Import List
2. Click Choose File and select your CSV
3. If the format isn't auto-detected, select Custom CSV
4. Map your columns:
   • Email column
   • Reason column (optional - defaults to hard_bounce)
5. Click Import
6. Review the import summary

Import Process

• Automatic Deduplication: Duplicate emails are skipped
• Email Validation: Invalid email formats are rejected
• Reason Mapping: Common reason strings are automatically mapped
• Privacy: Email addresses are hashed for storage

Removing Emails from Suppression List

When to Remove

• An email address was incorrectly added
• A hard bounce was temporary (e.g., mailbox full, now resolved)
• You've verified an address is valid again
• A recipient wants to resubscribe

How to Remove

1. Find the email in the suppression list table
2. Click the Delete (trash) icon in the Actions column
3. Confirm the removal
4. The email is immediately removed and can receive emails again

Warning: Only remove emails if you're certain they should receive emails. Removing hard bounces or complaints can hurt your sender reputation.

Automatic Suppression

The system automatically adds emails to the suppression list when:

Bounce Events

• Hard Bounces: Permanent delivery failures (invalid address, domain doesn't exist)
• Soft Bounces: Temporary failures (mailbox full, server down) - may be added after multiple failures

Complaint Events

• Recipient clicks "Report Spam" or "Mark as Junk" in their email client
• Email service provider reports a complaint

Unsubscribe Events

• Recipient clicks the unsubscribe link in your email
• Unsubscribe request is processed

Suppression During Campaigns

When sending a campaign:

• All emails on the suppression list are automatically excluded
• No manual filtering needed
• Suppression happens before emails are queued

Best Practices

Regular Maintenance

1. Review Regularly: Check your suppression list monthly
2. Monitor Growth: Watch for sudden increases in suppressions
3. Investigate Patterns: Look for common domains or patterns in bounces
4. Clean Up: Remove incorrectly added emails promptly

Import Management

1. Import Before Major Campaigns: Update your suppression list before large sends
2. Verify Sources: Only import from trusted sources
3. Test Imports: Import a small test file first to verify format
4. Keep Backups: Keep original import files for reference

Address Hygiene

1. Validate on Entry: Validate email addresses when adding contacts
2. Double Opt-In: Use double opt-in to reduce invalid addresses
3. Monitor Bounces: Address bounce issues quickly
4. Respect Unsubscribes: Never remove unsubscribe entries manually

Compliance

1. Honor Suppressions: Never send to suppressed addresses
2. Process Unsubscribes: Ensure unsubscribe requests are processed
3. Monitor Complaints: Investigate and address complaint causes
4. Document Actions: Keep records of suppression list management

Troubleshooting

Import Fails

Problem: CSV import shows errors

Solutions:

• Check CSV format matches requirements
• Ensure email column is present
• Verify email addresses are valid format
• Check file encoding (should be UTF-8)
• Review error messages for specific issues

Email Still Receiving Campaigns

Problem: Email is on suppression list but still receives emails

Solutions:

• Verify the email hash matches (check exact email address)
• Ensure suppression was added before campaign was created
• Check that campaign is using correct contact groups
• Refresh the page and check suppression list again
• Contact support if issue persists

Can't Remove Email

Problem: Delete button doesn't work or email reappears

Solutions:

• Refresh the page and try again
• Check browser console for errors
• Verify you have permission to modify suppressions
• If email was auto-added from a recent event, it may be re-added
• Contact support if issue persists

Import Shows Wrong Counts

Problem: Import summary doesn't match expected numbers

Solutions:

• Check for duplicate emails in your CSV (they're skipped)
• Verify email format is correct
• Check that reason values are supported
• Review skipped/error counts in import summary
• Some emails may already be in the suppression list

High Suppression Rate

Problem: Many emails being added to suppression list

Solutions:

• Review bounce reasons in campaign analytics
• Check email address quality in your contact groups
• Verify your sending domain configuration
• Review email content for spam triggers
• Consider email validation service
• Check for list hygiene issues

Understanding Suppression Reasons

Hard Bounce

• Meaning: Permanent delivery failure
• Common Causes:
  • Email address doesn't exist
  • Domain doesn't exist
  • Mailbox is disabled
• Action: Remove from contact list, don't resend

Soft Bounce

• Meaning: Temporary delivery failure
• Common Causes:
  • Mailbox full
  • Server temporarily unavailable
  • Message too large
• Action: May retry, but multiple soft bounces become hard bounces

Complaint

• Meaning: Recipient marked email as spam
• Common Causes:
  • Unwanted emails
  • Poor list hygiene
  • Misleading subject lines
• Action: Review email practices, never resend to complainers

Unsubscribe

• Meaning: Recipient opted out
• Common Causes:
  • No longer interested
  • Too frequent emails
  • Content not relevant
• Action: Respect opt-out, remove from marketing lists

Privacy and Security

Email Hashing

• Email addresses are stored as MD5 hashes for privacy
• Only the first 12 characters of the hash are displayed
• Original emails cannot be recovered from hashes
• This protects recipient privacy while maintaining functionality

Access Control

• Only account owners and authorized users can manage suppression lists
• CSR users have read-only access
• Suppression list is per-user (not shared across accounts)

Related Guides

• How to Create an Email Template
• How to Create an Email Campaign