1. Overview

Suppression lists in MassMailer (within Salesforce CRM) prevent emails from being sent to specific recipients due to bounces, unsubscribes, spam reports, or manual exclusions.


2. Suppression List Categories

MassMailer supports four primary suppression types:

2.1 Bounce Suppression

  • Triggered when emails fail to deliver due to:

    • Invalid email addresses

    • Non-existent domains

  • Classified as permanent failures

  • These addresses should never be retried

2.2 Spam Suppression

  • Occurs when:

    • Recipients mark emails as spam

    • Mail servers auto-filter emails

  • Impacts sender reputation negatively

2.3 Unsubscribe Suppression

  • User-initiated opt-out from email communication

  • Required for compliance with:

    • GDPR

    • CAN-SPAM

  • Must always be honored

2.4 Manual Suppression

  • Defined internally by the organization

  • Use cases:

    • GDPR restrictions

    • Internal blacklist

    • Catch-all email addresses

3. Data Requirements for Import

Before importing suppression data into MassMailer, ensure the .csv file contains the following fields:

Field NameMandatoryDescription
Email Address✅ YesTarget email to suppress
Suppression Type✅ YesCategory (Bounce, Spam, Unsubscribe, etc.)
Reason❌ NoAdditional context

Example CSV Structure

Email, Suppression Type, Reason
user1@example.com, Bounce, Invalid domain
user2@example.com, Unsubscribe, User opted out

4. Import Workflow

4.1 Navigate to Suppression Module

  1. Open MassMailer app

  2. Go to MassMailer Suppressions Tab

  3. Click Import

4.2 Launch Data Import Wizard

  1. Select Custom Objects

  2. Choose MassMailer Suppressions

  3. Click Next

4.3 Select Import Action

Choose one:

  • Add New Records ✅ (Recommended)

  • Update Existing Records

  • Add & Update Records

4.4 Upload CSV File

  1. Drag and drop .csv file

  2. Click Next

4.5 Field Mapping

  • Auto-mapping occurs by default

  • Verify:

    • Email → Email Field

    • Type → Suppression Type

  • Adjust manually if needed

4.6 Review & Execute

  1. Review mapping and data

  2. Click Start Import

4.7 Validation

  • Navigate back to Suppressions Tab

  • Confirm records are successfully imported

5. System Behavior After Import

Once imported:

  • Suppressed emails are automatically excluded from campaigns

  • Applies to:

    • Bulk email campaigns

    • Automated workflows

    • A/B testing sends

  • No manual filtering required


7.  Conclusion

Suppression list management in MassMailer is essential for maintaining a clean, compliant, and high-performing email marketing system within Salesforce.

By properly importing and maintaining suppression data:

  • You ensure only valid, engaged users receive emails

  • You protect your brand reputation

  • You maximize ROI from email campaigns

For more information, you can refer to the blog post.