Whenever you get a connection error when sending via SMTP like The most common reason for this problem is that the ESP (Email service provider) you have defined in your delivery settings doesn’t accept one of the used email addresses. Change the from-address, the reply-to, and the bounce address to the email you use to […]
If you’re sending your campaigns you’ll get sometimes subscribers marked as error
In some rare cases, Mailster shows this error after an ajax request doesn’t respond to a valid JSON: This error is often caused by third-party plugins or some unexpected server outputs. Please open the developer console to see the problem with this error.