What is the optimal character length for email subject lines and preheaders across different devices and email clients?
The optimal character length that will be visible across all tested devices and email clients is 33 characters for your subject lines and 37 characters for your preheaders. This ensures that your key message is displayed fully whether your recipient is using an iPhone 14 with Apple Mail, Google Pixel 7 with the Gmail app, or even desktop versions of Gmail and Outlook.