There are three queues to a channel:
Inbound - Green source node (Socket, File Reciever, etc)
Processing - Blue Mapping nodes and Yellow Condition Nodes.
Outbound - Purple Destination Nodes
When you pause a channel:
Inbound Queue - The source will continue to recieve or look for new messages and the inboud queue will continue to accept new messages.
Processing Queue - All Blue Mapping and Yellow Condition Nodes are stopped when channel is paused and no messages will be processed from the inbound queue
Outbound Queue - Purple Destination Nodes are not stopped and will process any messages already in the queue when the channel is paused.
Note: The Nodes that are stopped when channel is paused will show in red with a power symbol indicating they are not running. The pause only stops the mapping node.
If you want to stop a destination node you can right click on it and select "Disable Node". You can also stop them via a scheduled script: https://www.qvera.com/kb/index.php/1127/there-way-to-stop-or-start-destination-node-at-scheduled-time?show=1127#q1127
If you want to stop the source node you can right click and select "Disable Node".