I've been looking for a specific explanation on how many messages Google queues for a particular offline device before it starts dropping them? I've read that only 4 unique collapse keys can be queued for a device at a time but I just tested sending 5 messages with unique collapse keys and when i brought my device online, I got all 5. I need to know how many messages I can expect Google to hold on to and also how many unique collapse keys I can have queued at once.
Thanks a lot for your answers.