You'll want to get used to seeing Spark's splash screen, as it pops up nearly every time the app is launched--a real buzzkill when you just want to dive straight into new emails. The app also isn't particularly good about marking unviewed messages as read when deleted via Notification Center, or clearing notifications from the lock screen once opened with a swipe for that matter.
Despite these complaints, Spark is a well-made, very solid email client with a whole lot of potential. Aside from the aforementioned bugs, the biggest thing missing is native iPad support. I'd also love to see Readdle add spam and other categories to Smart Inbox mode, which would further help tame unruly inboxes.
Spark takes a smarter approach to streamlining mobile email that won't alienate longtime users, but suffers from a variety of version 1.0 gremlins.
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