The campaign was "inappropriate and ill-conceived," Chen wrote in a blog post. T-Mobile e-mailed customers last week in a campaign to encourage BlackBerry customers to switch to an iPhone.
BlackBerry users on Twitter responded with a campaign of their own, tweeting at T-Mobile President John Legere with the hash tag #CHOOSEBLACKBERRY10. Legere responded with his own tweets, saying, "We may still send e-mails w/device choices, but you don't have to give up your BB."
Chen said BlackBerry is grateful for the support, and but isn't too happy with T-Mobile.
"I can assure you that we are outraged too," he wrote. "What puzzles me more is that T-Mobile did not speak with us before or after they launched this clearly inappropriate and ill-conceived marketing promotion."
Chen also promised a special offer, "very soon," for its "loyal customers on the T-Mobile network."
T-Mobile has not been shy about how it feels about BlackBerry. With the smartphone maker's popularity waning, the carrier announced in September that it would be pulling its stock of BlackBerry phones from physical stores. But, customers can still order some of the devices, including the Q10 and Z10, through the stores.
A T-Mobile spokesperson said it will start offering free expedited shipping for BlackBerry devices by Friday. "We are happy to be a BlackBerry partner and apologize for any confusion," according to a statement from T-Mobile.
Update, 7:51 p.m. PT Added statement from T-Mobile.