Push wait mail routing

we have a domino server in our dmz that all our customers currently connect to and replicate with, our server cannot connect directly to the customers as their servers are behind closed firewalls.

we want to setup notes mail routing to the customer domains and i just wanted to check that Push Wait is the correct type of router connection for our server, ie ours has to sit and wait for thier server to connect and pull any pending mail down, or does it mean it only tries to send when the destination server connects (which isn’t going to work).

i also need to confirm that the customers would set their connection up using Pull Push