4.3.2 The maximum number of concurrent connections has exceeded a limit, closing transmission channel

4.3.2 The maximum number of concurrent connections has exceeded a limit, closing transmission channel

This error cropped up in the protocol log for an external (internet-facing) receive connector.s

The receive connector this was happening on was receiving traffic solely from a smarthost and hence typically would have a fair number of connections originating from a single source.

To remediate this try:

Get-RecieveConnector "your-connector" | FL *MaxInbound*

and changing to something like:

Set-ReceiveConnector "your-connector" -MaxInboundConnection 5000 -MaxInboundConnectionPerSource 500 -MaxInboundConnectionPercentagePerSource 20