Send Problems On Remote Installation

I now have two instances one with my source queue, and the target on a seperate instance. I have endpoints setup and have granted connection to the endpoint to the sql service account from the source system and vice versa. I have routes in the source system pointing to the endpoint on the target system. I have a route on the target system pointing to the endpoint on the source syste. I have routes in msdb that point to local with the correct service name.

Now, when I try to send a message, it fails and I get an error back in the source queue. I setup tracing on my target instance and added all the broker events. I get an error saying that "userid 0 does not have send permissions for the target service". User ID 0 is, of course, public. When I trace for security events I can see a DB obejct Access event that shows the loginname is sa and the dbusername is public. Now I have to say that this seems very strange for the server login to be mapped to sa, but use a database principal of public. When I grant send on <my servicename> to public it all works.

So I have two questions,

1) I don't have to grant send to public to make the cross instance communication work do I?

2) What did I miss in config that is causing public to be getting invoked as the db user in my target database.

Thanks!