Readdle today released a new addition to its giant collection of productivity apps for iOS with the debut of Spark. Spark is described in short as “fast and smart email for your iPhone” while its core features include tons of customization options and intelligent notification and filtering options that help take the stress out of email. Though Spark is only the latest third party email app to land on the iPhone, it is the first solid email client I’ve used on the Apple Watch so far. How does it compare to Apple’s own Mail app in this case? Out of the box, Spark lets you easily plug in your iCloud, Google, Exchange/Outlook, or Yahoo email account to offer a unified inbox experience. I set up Spark using my Google Apps account, and the login screen featured 1Password’s extension for filling in my email and password with Touch ID. Very handy.

Next up, Spark asks you which type of notification you prefer from the iPhone email app. You can choose between three options: standard notifications, smart notifications, or no notifications. I typically don’t want to miss a single email on my Mac, but Spark’s smart notification feature promises to only notify you about emails you care; this seems fine for iPhone and even better for Apple Watch.

After first plugging in your email credentials, you land in your inbox for the first time. Spark resembles Google’s Inbox email app with a floating compose button on the bottom right, and you can quickly swipe threads left or right to archive/delete or pin/snooze a message similar to Dropbox’s Mailbox app. The toolbar at the top lets you jump into a view to see only your snoozed messages or archived messages.

You can also drill into search from here with natural language search options like ‘forwarded emails from Mark Gurman in March” and Spark will show you just that. A star button lets you favorite your searches for easily using the same query again in the future, or you can reuse recent searches again without favoriting.

Spark lets you switch between your smart inbox and full inbox from the basement menu on the right side. The smart inbox is useful as it separates new messages from the rest of your inbox; Spark can also separate messages from important people and newsletter subscriptions. From here you can also view an inbox that only shows attachments or any of your other mailboxes associated with your email account.

The settings section here is where the real customization begins. You can set emails to archive after you’ve seen them, change what actions goes with which swipe directions, toggle email read receipts on or off (neat!), setup different email signatures which Spark lets you easily choose when writing messages, and plug in other services. At launch, these services include Dropbox, Google Drive, Box, OneDrive, Readability, Pocket, Evernote, OneNote, and Instapaper.

Over on the Apple Watch, Spark is even more impressive. Unlike Apple’s Mail app on the watch, Spark allows you to actually respond to messages that you receive using quick replies or dictation. Apple’s Messages app offers the same features, but Apple’s Mail app on Apple Watch limits responses to flagging, marking as unread, or deleting.

While I usually don’t want to be dictating longer messages into my watch, the ability should be just as convenient as replying to text messages or iMessages as you can already do. Spark isn’t lighting fast on the Apple Watch as it relies on pulling information from the iPhone, but it works well enough considering that’s the state of third party apps for now. I haven’t seen a better Apple Watch email app yet.

There’s certainly a whole lot more to Spark’s customization options and smart filtering behaviors, but on the surface Spark is an easy-to-use and potentially more capable email app on the iPhone. On the Apple Watch, Spark is a must-have if you want to do more quick actions than what Apple allows in its own app.

Spark is available completely free for iPhone and Apple Watch from the App Store.

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