server rejected one or more recipient addresses. The server response was: 550 5.7.1 Unable to relay

The server rejected one or more recipient addresses. The server response was: 550 5.7.1 Unable to relay for

Reason.

your connection ip or relay ip is not matching with ip you are using to send mails.

OPen iis from control-panel->administrative tools->internet information services.

now right click "default smtp virtual server" & selcect properties as shown in following image.


now select the appropriate IP in connection drop down that should match with the IP you are using to send mail.

now select the "Access" tab you will see the screen as follow



in Connection and Relay add same IP.

it will resolve the problem

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