I'm getting a weird issue with email coming from yahoo.com.au
Sporadically email from yahoo.com.au will not arrive and the sender will get a bounce email with "unreachable for too long" in the error information.
The yahoo.com.au sender will add cc addresses to the email and it will arrive at the other recipient but not at a recipient at my Exchange server. But it's not consistently always happening.
I created a test yahoo.com.au email account and sent tests through and they came in.
I have added any yahoo.com.au IP address to the allow list in Forefront and Exchange antispam.
Do you guys think it's my Exchange server?