Deliverability rates by domain refer to the percentage of emails successfully delivered to recipients’ inboxes, categorized by the domain of the email address. This metric is used to measure the effectiveness of email campaigns and the ability of email service providers to deliver emails to different domains, such as Gmail, Yahoo, or Hotmail. A high deliverability rate by domain indicates that a large number of emails are reaching their intended recipients, while a low rate may suggest issues with spam filters or email authentication. Monitoring deliverability rates by domain is crucial for businesses to ensure their messages are being received and read by their target audience.