In rolling out their popular new email client, the developers behind Mailbox played it about as safe as anyone possibly could. A long waiting list stands between iPhone owners and access to the sleek, innovative app. But today it's become clear that this phased approach has failed to shield Mailbox from complications. For the last several hours, Mailbox has been down, delivering a "having trouble connecting" message to its rapidly-expanding crowd of users. On Twitter, developers are attributing the hiccup to "an unusual server problem" and have promised a timely fix.

The team admits troubles have been ongoing for ten hours or so, but we can report that some Verge staff members began noticing issues last night. Unfortunately, owing to the pivotal role email plays in many of our lives, some users may not be willing to afford Mailbox a second shot at getting it right. A "hiccup" quickly evolves into a monumental problem when you're unable to read your messages the moment they arrive. Mailbox's own Gentry Underwood recognizes as much. "We need to stay up. It’s a big responsibility, and it keeps us up at night," he recently told The Verge. For the hundreds of thousands of people still clamoring to give Mailbox a try, this early snag won't be a death blow. But if Mailbox is to become the de-facto app for Gmail users, it needs to eliminate any scenario that forces us back to other options. It's not getting off to a great start.

Update: Mailbox's developers have acknowledged the outage in a blog post.

We’re currently seeing intermittent issues with our servers syncing mail. We’ve paused filling reservations so that we can focus on a fix.

If you’re currently using Mailbox, you’re most likely seeing a message that says "Having trouble connecting, please try again soon." Don’t worry, any messages that you take action on or any new emails you create should not be lost. Once we have resolved the issue your Mailbox will simply update and process all actions you’ve taken inside the app.

The team is working on resolving this now, and we’ll let you know as soon as we’re filling reservations again. We hope to get things moving shortly.

Thank you for your patience,

The Mailbox Team

Update 2: Mailbox performance appears to be returning to normal, though it appears the issues haven't fully gone away yet — some users on Twitter are still noting problems when trying to using the app.