Emails Rejected to specific user

Hi All,

We have been emailing a customer invoices for a number of years successfully and recently the customer has some issues with there email where the emails were bouncing back. They have since fixed the issue but we still cannot get emails from accountright@app.myob.com to go through to that email account.after a short period we get a email saying it was rejected.

Their IT team have checked their email server logs and report that the email is not even reaching their mail server. We have also tested emailing from our business accounts and the the emails are received correctly. It only seems to be affecting emails from MYOB's inbuilt email service. We have also tested from my friends business and have the same issue.

Has anyone got any ideas on what else we can do or what their IT team can check?

The customer would prefer not to use an alternate email.

Thanks