Outlook.com Aliases

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In 2013, I published this article on NM’s Tumblelog and in 2021, I migrated it to Infinite Ink. I have not yet updated it and, unfortunately, some of the links are broken.


Why I started using Outlook.com aliases

Now that Outlook.com supports IMAP, I’ve decided to try using an Outlook.com alias as my public email address. I’m doing this mainly to test Outlook.com’s filtering and IMAP capabilities, but also because it’s time for a new public email address for me—​I like to keep the profilers on their toes!

What is an Outlook.com alias?

Each Outlook.com account has a primary email address and zero to nine non primary email addresses. Possible domain names for Outlook.com aliases include @outlook.com, @hotmail.com, @msn.com, @windowslive.com, @live.com, @live.tld, and @outlook.tld. Some of these, such as @msn.com and @windowslive.com, are not available for new aliases. You can also set up an address that’s hosted at another (non-Microsoft) email service provider as an Outlook.com alias. Microsoft calls all ten of your addresses—​including the primary address—​aliases. Many email service providers, including Outlook.com, support plus addressing, but note that Microsoft does not call plus addresses aliases.

As of 2013 April 17, you can use any of your Outlook.com aliases to sign in to your Microsoft account. This means that each of your aliases is also a Microsoft sign-in ID.

Tips for setting up and using Outlook.com aliases

  • To learn some (but not all!) about Outlook.com aliases, see Microsoft’s Use aliases to add email addresses to your account. That page includes information about how many aliases you currently can have. At the moment, you can have 10 aliases (and create at most 10 per year), but it used to be that you could have 15 aliases (and create at most 5 per year).

  • Since you can create at most 10 aliases per year, think carefully before you create an alias. I created 10 aliases and deleted some, but won’t be able to create any more for a year. ☹

  • When you create an alias, you have the option of having messages that are sent to that alias delivered to a specific IMAP-accessible folder. The Outlook.com rule that is created to do this is:

    Move messages to foldername if to or cc line contains word "alias@outlook.com"

    This rule does not catch messages that are Bcc’d to alias@outlook.com and there is currently no way to create an Outlook.com rule to catch Bcc’d messages. Many email service providers, such as Fastmail.FM, let their users filter Bcc’d messages by exposing incoming SMTP envelope information in X- headers.

  • When you use the Outlook.com web app or a device-based EAS (Exchange ActiveSync) app to send an email message:

    • You can choose what alias will be in the From: header by selecting one from a pull-down list of all your aliases.

    • The From: header will be From: Display Name <alias>.

    • The Display Name is the same for all your aliases.

    • If you use an email signature, it is the same for all your aliases. You can change your signature while composing a message.

  • When you use a device-based SMTP/IMAP app to send an email message:

    • The From: header will be From: Name <defaultfromalias>.

    • The Outlook.com outgoing SMTP server does not change the Name that you have specified in your app. This means that you can specify anything you like for the Name.

    • The Outlook.com outgoing SMTP server automatically, and without warning, changes your From address to your Default From address. To specify your default From: address, go to the Outlook.com Mail web page and in the upper right corner, choose:

      Gear Icon > More Mail Settings > Your Email Accounts

      At the bottom of that page, you can specify your Default "From" Address.

Dear Microsoft

Dear Microsoft,

Thank you for supporting IMAP and letting us create up to ten aliases. Here are five wishes related to Outlook.com aliases.

  1. If I’m using a device-based SMTP/IMAP app and try to send a message that is From an alias that is not my Default "From" Address, you should refuse to send it. Automatically changing the From address, which is what you do now, is potentially dangerous to someone who is trying to be anonymous or pseudonymous.

  2. When I use a device-based SMTP/IMAP app, let me send From any of my aliases.

  3. When I use the Outlook.com web app or device-based EAS app, let me set up and automatically use a different Display Name for each alias.

  4. When I use the Outlook.com web app or device-based EAS app, let me set up and automatically use a different signature for each alias.

  5. In the header of each incoming email message, please inject header lines that expose the incoming SMTP envelope information. This will make it possible to create rules that catch messages that were Bcc’d to an alias. An example of such a header is X-Envelope-To: alias@outlook.com

Thank you!
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