TPG SMTP Relay - 550 Relay Denied

[OggyP]

Hi, I have been using the SMTP relay offered by TPG to relay all my emails from my own mail server on my local network, connected via TPG to the NBN. Recently the SMTP relay has been denying my emails (see below). How can I resolve this issue so that my email server will be able to again send emails? Thank you for any help.

Remote-MTA: dns; mail.tpg.com.au
Diagnostic-Code: smtp; 550 mf-505: Sender Policy - Relay Denied

host mail.tpg.com.au[52.63.237.70]
    said: 550 mf-505: Sender Policy - Relay Denied (in reply to MAIL FROM
    command)

[BasilDV]

Hi @OggyP 

We'd like to check on what we can arrange for you.

Please send us a private message with your account details.

BasilDV