Additionally, when servers are merged, the younger servers get better merged server rewards packs. I believe it is something like 200-400 coupons for the oldest servers in a merge and up to 2,000 coupons for the newer servers, though this can vary based not he exact ages of the servers in question, so there are better rewards given out for the younger servers.

It doesn't get sent out so much as it's available. There should be a new icon at the top of your screen labeled something like "Merged Server Compensation" or something like that. Look for that.