Spotify is sending emails to iPhone customers encouraging them to stop paying for its premium music streaming service through Apple's App Store. The company is advising people to sign up directly through the Spotify website as a way to avoid the 30 percent fee Apple charges on in-app subscriptions.

Spotify’s ad-free paid tier costs $9.99 per month, but the company charges $12.99 if purchased at the iTunes App Store to offset the cut that Apple takes.

The email reads: "We like you just the way you are. Don't change. But if you want to change how much you pay for Spotify Premium, we're here to help. In case you didn't know, the normal Premium price is only $9.99, but Apple charges 30 percent on all payments made through iTunes. If you switch your payments to Spotify.com, there are no transaction costs and you'll save money."

The message then gives a 12-step tutorial explaining how to shut off auto-renew through iTunes and transfer a Spotify premium account to the web — something that can only be done once a current subscription lapses.

This is not the first time Spotify has clashed with Apple; in 2012, the company claimed Apple tried to prevent its US launch, and Spotify is widely believed to be behind the antitrust allegations that led to both EC and DOJ investigations into Apple's alleged anti-competitive practices.