Eddy Cue, Apple's services chief. AP Apple's software has been slipping in recent years, pioneering tech blogger Walt Mossberg argues in a piece published in the Verge on Wednesday.

Mossberg spent the most time slamming the built-in Mail app on the iPhone, a critical piece of software for many users.

The default mail app is "slow and unreliable," according to Mossberg, and making things worse, it doesn't seem to want to play nicely with Gmail, one of the most popular email services in the world with over 1 billion users.

In my experience, Mossberg is right: The built-in mail client on the iPhone has been lacking for a while.

Mossberg wrote:

Apple claims this is an issue beyond its control, or the control of any other email app vendor, because Gmail uses nonstandard technology that gives a speed advantage to the search giant's own apps and sites. (Google has told me otherwise in the past.)

Apple's excuse reveals its anxiety over a growing focus for the company: online services. This is an area where Apple trails its big competitors: Google still owns maps, Facebook Messenger regularly tops the App Store charts, and Spotify continues to gain new subscribers even as Apple pushes its music-subscription service.

For what it's worth, I don't buy it. I use Microsoft Outlook on the iPhone, and it works perfectly fine with Gmail. Outlook is snappy and modern, complete with threaded messaging, email snoozing, and sophisticated filtering that ensures that what lands in my inbox is an actual message from another human. It's what I want from Apple's built-in app.

And I'm not the only person who thinks Outlook is a significantly better email client than Apple's. Business Insider's Stephen Tweedie agrees, as do several other writers here and at our sister publication, Tech Insider.

For years, Apple was happy to provide the best physical computer or phone for users to access services from internet-focused companies like Google. But as the company looks for new growth avenues as iPhone and Mac sales stall, it's realizing that it needs to catch up — which is why it's building three new data centers in the next two years.

CEO Tim Cook is fond of saying that there are certain achievements that only Apple can pull off, thanks to its integration of hardware, software, and services. But increasingly, competitors like Microsoft, Google, and Amazon can do all three as well, and they have a decisive advantage over Apple when it comes to services. Catching up will be a bigger challenge than fixing a buggy Mail app.