Microsoft knows you're making throwaway e-mail accounts, and wants to make that process easier.

Today, Hotmail is getting a new feature aimed at "e-mail enthusiasts," which lets anyone create multiple e-mail accounts that can be read, replied to, and managed from their everyday e-mail inbox. These additional e-mail addresses can be had in the same manner as signing up for new accounts, but they require no extra log-ins or upkeep.

The idea is to give users a safe way to provide third parties with an e-mail address, without giving up the address they've provided to family and friends, which, if compromised, can end the usefulness of that particular account.

"Today we all often have multiple e-mail accounts for many different reasons," Windows Live director of product management Dharmesh Mehta told CNET in a phone interview yesterday. "One of which is that I don't want to give my real address out to any site in the world. I might be worried they'll spam me with newsletters, or they might resell it to other marketers. Who knows what can happen"

The other problem, Mehta said, is balancing a single e-mail address with work, family and friends, and everything else you're doing on the Internet. "If I'm a hardcore gamer in one environment, and a conservative professional guy in another environment, there are different reasons for multiple accounts," Mehta explained.

The solution Microsoft's Hotmail team came up with was to make use of some of its existing technologies like account sign-up, message filtering, and multiple e-mail address integration to give users these aliases within the same account. Each user can create up to five aliases, any of which can be deleted and replaced with another at any time. Over time, Microsoft will increase that limit to 15 aliases per account, making it so that the true heavy users won't need to juggle between two or more Hotmail accounts.

Making an alias in Hotmail is similar to signing up for a new account. Users can pick any name that&39's free and open.

Aliases joins an existing multiple e-mail address feature offered in both Hotmail and Google's Gmail that uses a plus symbol after a user name, but before the @ symbol. Users would then add any word after the plus symbol to create an identifiable address (e.g. Josh+newstip@Hotmail.com). This lets messages get filtered into folders, while also providing a way to see if that retailer you bought something from sold your address to a third party.

However the big problems with that system are that it's easy to see the person's real address, and some sites and forms might not let you use the plus symbol. In this sense, Microsoft's new system promises to offer a higher level of privacy along with compatibility when running across sites that won't let you use special characters.

Mehta said he expects the feature to appeal more to the tech enthusiast crowd, which the company intends to better serve over the course of the year, while still appealing to the consumer crowd, which makes up the bulk of Hotmail's users.

"Hotmail needs to serve two audiences that are somewhat pretty different," Mehta said. "One is this set of mainstream consumers, the average person who uses e-mail. The second is the tech enthusiast who wants different things compared to the mainstream user who wants good features but generally is like 'don't change my stuff, don't modify things, don't mess with it.' The enthusiasts are like 'give me a new feature every hour, and I'd love it!'"

Mehta said that the plan with Hotmail going forward is to "win with both these audiences," while finding a release cycle that suits both. But as Mehta explained, Hotmail also needs to move beyond the competition. "For us that's really versus Gmail. So how do we start to beat Gmail in a couple of different key scenarios certain customers are just going to like more" The first step in that direction, Mehta said, is aliases.

Microsoft says the new feature will hit all user accounts worldwide this afternoon.

Update at 3:15 p.m. PT: As commenter Sroar points out, Yahoo has a similar alias feature as part of its paid Plus service.

Also, the feature is already live in one of our test accounts. Here's what the sign-up screen looks like (note that you can pick between Hotmail.com and Live.com as the domain):

Signing up for an alias.