I have set up a mail forward from my alerts@ address to monitoring@. I successfully verified the forward and it had a green dot next to it. Every time I send an email to the alerts@ email address though it fails, and the forwarding is disabled (green dot changes to a grey dot).

I suspect the problem is caused because I have a split domain. alerts@ is a Zoho address, and monitoring@ (on the same domain name) is an Office 365 address. The split domain works fine normally, but it seems forwarding rules can't handle sending to the split domain.

Can someone please take a look and try to fix this problem?