Failed To Email About Order Status To Customers

General General Questions
1

Our customers can not receive any email about order info after ordering, but they can receive email about registration details

The notification:
ErrorMessage could not be sent.

Mailer Error:
440,SMTP server error:
2

Our customers can not receive any email about order info after ordering, but they can receive email about registration details

The notification:
ErrorMessage could not be sent.

Mailer Error:
440,SMTP server error:

Hello.

Please contact your mail provider on this case, for the correct SMTP set up.