Office 365 – Plus Addressing – Updated

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What is Plus addressing?

Plus addressing or subaddressing is available in Exchange Online. Plus addressing is using a unique, dynamically created receive-only email addresses for mailboxes.

  • Basic syntax of an SMTP email address: @. Example, JohnD@domain.com
  • Plus addressing syntax: +@. Example, JohnD+statements@domain.com

The original email address must be valid one. The +tag value is arbitrary, although regular character restrictions for SMTP email addresses apply.

Here is a scenario, Let’s say the users’ email address is JohnD@domain.com. User can use plus addresses as unique addresses for services that you sign up for, right after the local part (JohnD) and add (string) of choice. So for instance, to receive all bank statement, the user can end up with something like this: JohnD+statements@domain.com

Plus addressing Limitations

When using plus addressing, there are a few things to keep in mind:

  • Plus addresses aren’t aliases in Exchange Online
    • Hence, it can be used only to receive messages and not send them
    • It does not resolve to a user’s name in Outlook clients, so it is easily identifiable in the To and CC fields
  • In a Hybrid environment, plus addressing won’t work for on-premises mailboxes that do not resolve in Exchange Online
  • Web Developers are aware of plus addresses and some online forms/services won’t accept a plus sign in the email field
  • Some subscription services require the user use the original email address that they subscribed with
    • Can’t unsubscribe with plus email address

Enabling the feature

Enable using the Exchange admin center

  1. Login to the new Exchange admin center (https://admin.exchange.microsoft.com)
  2. In the left navigation menu Settings > Mail flow
  3. Select Turn on plus addressing for your organization, and then select Save

Note: After the plus addressing is turned on by default in April 2022, you will see the option Turn off plus addressing for your organization if you are following the above steps. Which will be unchecked meaning it is turned on. So placing a checkmark will turn off plus addressing. See screenshot below.

Enable using Exchange Online PowerShell

Before proceeding further make sure you are connected to Exchange Online,

$o365cred = Get-Credential
Connect-ExchangeOnline -credential $o365cred

The cmdlet uses below syntax:

Set-OrganizationConfig -AllowPlusAddressInRecipients $true

Disable using Exchange Online PowerShell

This setting will be effective only after plus addressing is turned on by default in all organizations starting in late April 2022. Before that happens, plus addressing can be disabled in the O365 tenant by using the AllowPlusAddressInRecipients parameter I described earlier with the value $false value. This can also be proactively set, you don’t have to wait for it to be turned on by default.

To disable plus addressing in the O365 tenant:

Set-OrganizationConfig -DisablePlusAddressInRecipients $true

Determine settings with PowerShell

To determine plus address related settings in the exchange organization:

Get-OrganizationConfig | Select *PlusAddress* | fl

Hope this helped you in understanding the plus address settings in O365.

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