Email suppression rate refers to the percentage of email addresses that have been removed or suppressed from a marketing campaign’s mailing list. This can occur for a variety of reasons, such as recipients unsubscribing, marking emails as spam, or having invalid or inactive email addresses. A high email suppression rate can indicate a lack of engagement or relevance in the campaign’s messaging, while a low rate suggests a successful and targeted approach. Proper management of email suppression rates is crucial for maintaining a healthy and effective email marketing strategy.