Subaddressing, also known as plus addressing, is a feature which allows an individual to append a tag to their email address by following this format: email+tag@domain.com. This allows a user to create as many unique email addresses as they would like, while still receiving them to their single inbox. This comes in handy when you want to filter through emails, as you could use a unique tag for every website, or use more general tags like “+shopping” or “+entertainment”.

Microsoft has added this capability to Exchange Online as of September of 2020. While it is not enabled for organizations by default (UPDATE: As of May 2022 this is enabled by default in new organizations) , nor can you enable it in the Admin Center, you may enable it using the Exchange Online PowerShell Cmdlets, which I will breakdown the installation and use of below.

How to Enable

The first step is to install the Exchange Online module on your workstation. You may do so by opening PowerShell as an administrator and running the following command:

Install-Module -Name ExchangeOnlineManagement

Note, you may get an error message about PowerShellGet, generally this just means the excution policy setting on your workstation is not allowing the install to run due to it being from a non-local source. You can get around this by running the following, then running the above command again:

Set-ExecutionPolicy Unrestricted

After the install has completed, you must import the module into PowerShell, like so:

Import-Module ExchangeOnlineManagement

Then you must connect to your organization, where user@email.com is an account with appropriate role assignments in your tenant:

Connect-ExchangeOnline -UserPrincipalName user@email.com

Then run the following to enable the subaddress option:

Set-OrganizationConfig -AllowPlusAddressInRecipients $true

If all is well, you may then disconnect using:

Disconnect-ExchangeOnline

I recommend setting the execution policy back to the default of Restricted when you’re done:

Set-ExecutionPolicy Restricted

That’s all there is to it, the change takes effect immediately so you can begin enjoying the ability to use subaddresses.

Update

As of May 2022, you may now also enable this through the Exchange Online Admin Center:

  • Navigate to the new Exchange admin center at https://admin.exchange.microsoft.com
  • Click on Settings
  • Click on Mail flow
  • Uncheck Turn off plus addressing for your organization
  • Click Save