We all know one of the biggest gripes about the iPhone is the inefficient notification system, and this frustration is doubled in regards to email because you don’t even get a pop-up message for incoming emails. You hear a ding, the badge number increases and that’s it. Opening the mail app is the only way to see whether you just received another spam message, an email from mom, or an important business email.

What a waste of time, right? Thankfully there’s Elert, a jailbreak app available in the Cydia store for $1.99 plus a short trial period. Elert pops up a small notification window in the lower right hand corner detailing the email’s sender, subject, and a snippet of the first line. It also allows you to expand the window to view the entire email and reply, all without leaving the app you’re in.

So if it’s another mass-email from your chain-letter obsessed coworker, you can hit the X and dismiss it for later. If it’s an urgent email from the boss demanding an immediate reply, tap the window and it expands to this:

Here it functions almost like the full-fledged mail app. You can delete, mark as read, compose a reply, or just launch the mail app. Now you might notice this is showing up on the lockscreen. Currently there is no way to disable it from showing up on the lockscreen, so if that’s a concern keep that in mind.

You can turn the app off and on easily by opening the Elert app after it’s been installed. You can also adjust the display time the preview window appears, from 5 seconds to 100 seconds. There’s also the option to adjust font color, but a bug is causing that to open a blank FAQ’s page. And unfortunately the actual FAQs link also opens a blank page.

So while it isn’t a perfect app, it’s been incredibly useful for me. I usually don’t like paying for apps, jailbreak or not, so I tried to forget about this one after the trial, but I found myself missing it so I gave in and bought it. Hopefully future updates will make the investment completely worthwhile.

I am running this app on an iPhone 4, iOS 4.1, but I’m not sure if it’s compatible with all versions. Let us know in the comments if it doesn’t work for you.

Will you make use of this app, or did you already have it installed? What features do you wish it had? Sound off in the comments below!