Mailer-daemon is e-mail server software that is responsible for message delivery. If you receive messages from mailer daemon it could indicate a problem with the recipient's e-mail address or server or an incorrect e-mail address. To remove the mailer daemon messages, you must find the source of the email problem.
Read the email you receive from mailer daemon and check the email address to make sure you entered it correctly. If the email address is correct, the address may no longer exist.
Read the details in the mailer daemon e-mail message. The first part contains the reason for the bounce and the second part contains the original e-mail message. If you find you typed the email address incorrectly, you can copy and paste the text from the mailer daemon e-mail message into a new e-mail.
To do this, highlight the original message in the mailer daemon message, right-click and select "Copy." Open up a new e-mail, click anywhere in a blank space, right-click and select "Paste." Type the correct e-mail address and send the email.
Check the domain name. For example, you may have typed email@example.com when you should have typed firstname.lastname@example.org.
Make sure your domain is not on a blacklist. There are websites that can check if your domain is blacklisted, such as Black List Alert or MX Toolbox.