Mobile payments company Square has launched a person-to-person payments service called Square Cash, the San Francisco-based company announced yesterday.

What does this have to do with Square’s mission to “make commerce easy”? Not much, but the service looks good and works well. Will that be enough to bring in users?

Square Cash works over email, as Google Wallet’s service does. Square users format their Square Cash emails this way:

• To: [email address]
• Cc: cash@square.com
• Subject: $ [amount]
• Send!

The money moves from one debit card to another, and, as with all P2P programs, there is a viral aspect: Users join Square to retrieve the money. The service works with any email program, Square said in its press release. There are no signup fees and no transaction fees, though TechCrunch reports that a previous iteration, discussed here, charged the sender $0.50. The limit that can be sent is $2500.

Debit card information need only be entered the first time, the it is stored. The money is transferred within “1 – 2 business days.” Verification for senders can happen using Facebook credentials, as well as other personal information.

Square has released an app, naturally called Square Cash, that puts this functionality, including pre-formatting the email fields above. It joins Square Wallet and Square Register in the App Store and on Google Play. So far its reviews are stellar: “Love it.” “Simple and sexy.” “I use this more than I ever thought I would.” This last comment is particularly impressive given that the app is just one day old.

Much of the attention around this service has focused on its threat to Venmo or Google Wallet, but P2P is fairly common functionality today, found in many mobile banking apps. Further, it’s not clear how this service benefits merchants, Square’s core customers, or will “make commerce easier,” as the company states its mission.

It’s not easy to see why a user not already wedded to Square would choose to join a closed system for functionality that can be found elsewhere, but Square has a superior user experience and has made payments a lot cleaner and simpler, so perhaps Square Cash will find some traction on that basis.