Ok, so the status says that it successfully sent the email, this means the problem is on the SMTP server end.
For some reason, the SMTP server is not relaying the email to that address.
The Way universal Email works is:
The PHP Page complies the email message, then hands it off to the SMTP server.
it is up to the SMTP server to relay the message to the recipient.
The response says it successfully passed the message on top the SMTP server, so it is the SMTP server that is not replying the email. you will need to contact the host for this one.