Every time I hear about a new email client that will support multiple services, I get excited. Is this finally the one that will free me from Gmail’s native iOS app? And time after time, I am disappointed, all because of one missing feature.

Microsoft just released a native iOS Outlook app. The app is beautiful. Like Apple’s Mail app, it supports most every pop and iMap service under the sun. Outlook looks great and features a Mailbox-like zero inbox scheme. There’s lots to like here. But that one missing feature. Aargh!

Here’s what’s missing: Gmail lets you create and manage labels. Labels are similar to folders, which allow you to organize your email. For example, I might have folders named MonkeyBiz, ToyCannon, and Investments. The first two are startups, the third where I keep track of my investments. With Apple Mail, Microsoft Outlook, and most traditional email clients, when an email comes in about an investment in MonkeyBiz, I have a choice to make. Do I put the email in the MonkeyBiz folder or in Investments? I can’t put it in both.

Gmail uses labels to solve that problem. I can attach any number of labels to an incoming email. If I get an email relating to a MonkeyBiz investment, I can label it as MonkeyBiz and Investments. If I look in my MonkeyBiz folder, I’ll see the email. I’ll also see it when I look in Investments.

Labels are incredibly useful. I just wish email clients supporting gmail would add this feature to the mix so I might have a choice of email clients.