Microsoft recently introduced an email alias feature for Hotmail which let people create multiple Hotmail addresses tied to the same account. It is pretty good, because unlike Gmail’s method of email alias (firstname.lastname@example.org) Hotmail aliases can be completely different from your primary Hotmail address, and hence do not reveal your true identity.
While Gmail's + feature allows creation of unlimited email aliases that can help sort incoming messages, it doesn’t hide your real email address. Spammers can easily write code that will automatically strip everything after the “+” sign and get your real Gmail username.
Hotmail's alias feature does not suffer from these problems. Incoming mails to your Hotmail alias end up in your primary Hotmail inbox, and outgoing mail from aliases including replies to an alias can be sent from the same inbox.
Unfortunately, Microsoft forgot to take into account email signature.
Hotmail allows users to configure a signature that is automatically added to the bottom of all outgoing emails. Many people include their name, phone numbers, IM handles, and other personal information, including their primary Hotmail username into the signature.
The problem is, if you send mails from your alias, you are also sending your email signature you setup for your primary Hotmail account. At this point, any privacy or anonymity achieved from the alias is gone.
So what should you do? Until Microsoft fixes this and allows setting up of different signatures from your aliases, you should stop using signature or edit it so that it contains no personally identifiable information.
Thanks Adam Overa