T-Mobile (NASDAQ:TMUS) never misses a chance to poke fun at its rivals.

Sometimes it's CEO John Legere mocking an outdated business practice on social media, and at others, it's him pointing out exactly how his company has decided to do something better or differently. T-Mobile, as led by its outspoken leader, more than happily casts light on its rivals' faults, and the results are usually informative and sometimes entertaining.

The latest bit of social media fun from the Un-Carrier comes at the expense of AT&T (NYSE:T) CEO Randall Stephenson, who recently botched an email interaction with a customer in spectacular fashion. It was a true case of AT&T acting like the big, traditional company whose users have no other choice, and to T-Mobile, calling a company out on that type of behavior is like shooting fish in a barrel.

What did AT&T'S CEO DO?
Stephenson's email address has long been a matter of public record. Ostensibly that's at least in part so customers can contact him. Alfred Valrie, an AT&T customer who buys home phone, wireless, Internet, and satellite TV from the company, learned the hard way that just reaching out to the CEO may not actually be a good idea, The Los Angeles Times reported.

Valrie sent an email to Stephenson sharing two ideas he had for the company -- unlimited data for DSL users and 1,000 text messages for $10 a month. In response, even though AT&T has a Code of Business Conduct that says that "our customers should always know we value them" and that "we listen to our customers," he got the a letter from an AT&T lawyer that said in part:

AT&T has a policy of not entertaining unsolicited offers to adopt, analyze, develop, license or purchase third-party intellectual property ... from members of the general public, Therefore, we respectfully decline to consider your suggestion.

The email, sent by Thomas A. Restaino, AT&T's chief intellectual property counsel, did thank Valrie for being a customer before telling him the company would not consider his ideas. That seemed fairly awful, and like something the company would correct when it realized its error, but AT&T compounded the mistake in its response to The Times from spokesman Georgia Taylor: 

In the past, we've had customers send us unsolicited ideas and then later threaten to take legal action, claiming we stole their ideas. That's why our responses have been a bit formal and legalistic. It's so we can protect ourselves.

That might be true, but it seems like there would be a way to explain that to a longtime customer who signed his email "Your lifelong customer, Alfred Valrie," without completely dismissing him.

How did T-Mobile respond? 
Unlike Stephenson, Legere openly responds to customers across a wide variety of social media platforms. To highlight his rival's error and show how his company is different, the T-Mobile CEO made his email public and pledged to listen to his customers.

"The entire Un-carrier revolution began by listening to customers. It's where we get our best ideas, and I want everyone to keep sending them my way at John.Legere@T-Mobile.com," said Legerein a press release. "It absolutely amazes me that Randall would tell a lifelong customer to basically go away and talk to my lawyers. I interact with customers on a daily basis so I can hear their ideas firsthand. It's called living in the 21st century."

T-Mobile also listed a number of existing ways it wants to hear from its customers -- and created some new ones.

"Starting today, AT&T customers can also send comments, concerns and genius ideas to IdeasforRandall@t-mobile.com or even better use #IdeasforRandall on Twitter and send @JohnLegere your ideas with the hashtag," according to the press release. "T-Mobile will keep the best ones and send Randall -- and his lawyers -- all the ideas we've already fixed."

Why is T-Mobile doing this?
In part, T-Mobile is doing this because Legere likes to kick his rivals when they do something so blatantly anti-consumer, and partially it's part of the company's careful effort to distance itself from the typical wireless industry way of doing business. Stephenson simply played into his rival's theme of "we care and they don't," and T-Mobile is making every effort to take advantage of it.

In some ways, this is all in good fun, and Stephenson would do well to take it that way and issue a playful mea culpa. AT&T is a big company, and big companies have a hard time shifting their thinking to reflect the changing social-media, customer interaction-driven world we all now operate in.

T-Mobile was smart to seize on this in a fun way, as its actions simply reinforce its marketing and Un-carrier image.