Payslips not sending to yahoo email addresses

I ran payroll as normal on Monday and sent the payslips out via email like I normally do. Yesterday I received emails from Microsoft Outlook for each of our employees who use an email address ending in yahoo.co.nz or yahoo.com, advising that each email was undeliverable.

I did nothing different to normal. These employees have been with us for months/years and I've not had this problem with them before. What has changed to cause this, and how do I fix this?

I went to attach the diagnostic information contained in the email from Microsoft Outlook, however it contains employee email addresses that I didn't want to put on here. I use MYOB Payroll 2023.1.