However, when I tried to add 2 users for the second domain, I got the message that the users exceeded the number of licenses I'd purchased. So I created aliases for them, instead. Then I logged in this morning and I see a message that says that the number of users (2) exceeds the number of licenses I've purchased.  That's craziness!

I did a search of the forums, and apparently this has been an issue for others, as well. One person posted a screenshot that shows the break down of the various levels of mail service, and it clearly showed the number of users for the "free" service was 5, but for the paid services it said "unlimited." The reply to that message said that has been fixed, but I just double-checked and today it still shows number of users is "unlimited" for the paid service. I do see that it also shows the price as $2/user / month, so obviously that leads to confusion. 

I thought I'd found a great solution, but this just isn't right. How on earth can you offer MORE for a free service than you do for a paid service? Please tell me you're going to fix this, so that I get what's advertised, so I don't have to find another solution. I don't even want "unlimited" users, but 5 per domain would be acceptable for the 10gb service level, I think. Heck, I'd be fine with 5gb for each user. 

Screenshot of the service levels, taken just minutes ago: