Email is not going to neomail if the forwarder fails, the error I get is pipe delivery process timed out

I have an email account a@mydomain.com and a forwarder
a@mydomain.com -> a@myisp.com

If it cannot deliver the message to a@myisp.com it doesnt deliver it to the box a@mydomain.com either and give the error "pipe delivery process timed out"

How do I fix this to still goto neomail if my ISP is down?