I am using PHP to connect to
apn
open connection to apple
loop over device-tokens
write to socket connection per device
end loop
close connection to apple.
loop over device tokens
create payload aggregating all devices
end loop
open connection to apple
write to socket ONCE with whole payload for 7000 devices
close connection
I've read that apple does care about the number of connections you make to their servers but I've never heard about any write limits. Also, I'm not sure about what kind of response you'd receive here, but it might be worth a try to see what happens. Maybe experiment with the sandbox push notification server, only using the device tokens of the production devices. Those phones should not receive any push notifications sent to the sandbox server and if the sandbox reports "delivered successfully", that would be a worry-free way to test.