I have set up some code to send out an email confirmation if I receive an email from a contact form. I am not receiving the email enquiries but sending out the responses. The only time I get an email is if I put in the correct domain i.e. firstname.lastname@example.org.
i've thrown an exception which says:
Mailbox unavailable. The server response was: 5.7.60 SMTP; Client does not have permissions to send as this sender [LO2P265MB0432.GBRP265.PROD.OUTLOOK.COM]