If a message receives the status “Failed”, it could not be delivered to the SMTP server you specified.

This can happen for the following reasons:

• the configuration for the SMTP server is incorrect, such as an incorrect password.
• too many emails have been sent within a short period of time, so that the limits of your SMTP server have been exceeded and it blocks further delivery attempts from PDF Mail Merger

To find out the exact reason of a failed delivery to your server, check your server logs or contact your IT department.