Microsoft Gives Tenants Opt-Out for Exchange Online Plus Addressing

Update Exchange Online Organization Configuration by April 17

Last August, I reported that Microsoft intended to introduce plus addressing by default for Exchange Online for all tenants. Exchange Online plus addressing is enabled for new tenants already. At the time, Microsoft’s target date to switch on plus addressing for all tenants was January 2022, but like many other Microsoft 365 features, the pace of development to create tenant-ready features can slow. This is especially true when customers affected by the change make their feelings known to Microsoft.

When released in preview in September 2020, tenants could opt-in to enable plus addressing early by updating the organization configuration. Microsoft is now making another setting available to allow tenants to opt-out of Exchange Online plus addressing before Microsoft starts to roll-out the change to make plus addressing available by default in mid-April 2022. The roll-out is scheduled to complete by mid-May.

Why You Wouldn’t Want to Use Plus Addressing

The usual reason why organizations don’t want to use Exchange Online plus addressing is that they’ve configured a bunch of mail-enabled objects with proxy addresses which contain the plus character. This was the only way that Exchange Online supported plus addressing in the past and it might be the case that organizations have deployed these addresses to support business processes.

The new method introduced for Exchange Online plus addressing removes the need to create and assign proxy addresses (which can only be done by administrators). Instead, end users can create their own plus addresses using clients which support the feature, like OWA and Outlook desktop. So far, I can’t see how to create a plus address using Outlook mobile. It’s also unlikely that non-Microsoft clients will support the feature in the short term.

Opt-Out for Plus Addressing

Announced in message center notification MC343788 on March 16, Microsoft says that if an organization wants to opt-out of plus addressing, they can do so by logging into a PowerShell session with the Exchange Online management module and running the command:

Set-OrganizationConfig -DisablePlusAddressInRecipients $True

Checking my tenant, I discovered that DisablePlusAddressInRecipients is set to False, which implies that Microsoft has already populated the setting to tenants. If you want to opt-out, you need to update it to True before April 17. In other words, a 30-day countdown clock has started for organizations to decide if they wish to use Exchange Online plus addressing before Microsoft switches on the feature.

When Microsoft deploys the plus addressing update to tenants, it will remove the old AllowPlusAddressInRecipients organization setting used to control the preview and respect the DisablePlusAddressInRecipients setting. If you find at that point that some proxy addresses exist which contain the plus character, you can disable plus addressing by updating the setting to True.

The Mail Flow settings section of the Exchange admin center (EAC) already includes a setting to enable plus addressing for an organization (Figure 1). Turning off plus addressing in the EAC doesn’t affect the DisablePlusAddressInRecipients setting. No doubt it will in the future. At least, that would be the sensible option.

Mail flow settings in the EAC include a setting to enable Exchange Online plus addressing
Figure 1: Mail Flow settings in the Exchange admin center

Check for Proxy Addresses

My January article includes some PowerShell code to check for the existence of proxy addresses with plus characters. You can use the script to help decide if you need to set DisablePlusAddressInRecipients to True. Otherwise, stay calm and wait for the deployment of Exchange Online plus addressing to start!

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