Today we ran into an interesting issue with our Exchange DAG. We have 2 datacenters with 2 DAG member in each datacenter. We have a file share witness in a third site and all sites are connected by MPLS connections. Today the MPLS circuit between the 2 datacenters started having intermittent connectivity issues. After about 20 minutes of very intermittent connectivity we stopped receiving emails from our outside email filtering service. when I attempted a telnet session to our mail servers I received the following message: 421 4.3.2 The maximum number of concurrent server connections has exceeded a per-source limit, closing transmission channel. Now I know I can adjust MaxInboundConnectionPerSource on the receive connectors. I think I would eventually exhaust whatever number I set it at though. My question is why would intermittent connectivity to DAG members that aren't doing anything cause inbound connections to be used up? What receive connectors do Exchange nodes use between each other? Would it be something for SafetyNet/ShadowCopy that would use a receiveconnector? If so which receive connector does it use?