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Exchange Team Blog
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Plus Addressing Now Available in Exchange Online

The_Exchange_Team's avatar
The_Exchange_Team
Platinum Contributor
Oct 27, 2020

As announced at Microsoft Ignite 2020, support for plus addressing is now available in Exchange Online. Thanks to our UserVoice site, this feature was identified as the number 1 request for Exchange Admins and we acted on that to bring it to Exchange Online.

Plus addressing allows users to dynamically create unique email addresses that deliver messages to a user’s mailbox, but are easily distinguished from messages sent to the user’s regular email address. There are two main use cases for this. Some customers want to filter incoming email and move certain messages to their own folders. Other customers have business solutions (such as support ticketing systems) that add a case ID to an email address to help track support threads.

Support is currently scoped to mailboxes with support for distribution lists and Groups expected in December 2020.

Plus addressing can be enabled for your organization via PowerShell. The instructions to enable it can be found here.

Additional documentation for the PowerShell command used can be found here.

We really hope you enjoy this new feature we’ve added to Exchange Online, and as always we want to hear your feedback, either here on the blog or over on UserVoice.

Sean Stevenson

Exchange Online Transport Team

Updated Oct 27, 2020
Version 3.0

18 Comments

  • Hi All

     

    In addition to ajc196 

    >How long after enabling Plus Addressing with Powershell should it take to function correctly? 

    >I enabled it for my org 2 hours ago, and it is still not even functioning internally. (user mailbox to user mailbox within our own tenant)

     

    I have enabled the Functionality in Powershell 5 Days ago and it still don't work. How long will it take until it's enabled?

     

    Regards

    Andres

  • ajc196's avatar
    ajc196
    Iron Contributor

    EDIT: Got some answers on my own since the feature finally started functioning in our org.

     

    I have a few questions:

     

    1) The detail "Support is currently scoped to mailboxes with support for distribution lists and Groups expected in December 2020" is worded oddly, or maybe by brain isn't functioning today. Just to clarify, this means that Plus Addressing currently works with user mailboxes, shared mailboxes, and resource mailboxes?  And that support for distribution lists and M365 Groups is *not* ready now, but coming in December?

     

    Tests worked to user/shared/resource mailboxes.

     

    2) Is Plus Addressing applicable to any valid SMTP address, or only primary SMTP addresses? (e.g. if my primary SMTP is andrew123@company.com and I have an additional address of andrew345@company.com, then andrew123+newsletters@company.com should obviously work, but would andrew345+newsletters@company.com also work?)

     

    Works for any aliases on a mailbox in my testing.

     

    3) If a mail security appliance (e.g. Cisco CES) does SMTP Call-Ahead to Exchange Online to validate an addresses' existence before delivery, will Exchange Online correctly validate an address using Plus Addressing since it's not an explicit/"real" address on Exchange Online mailboxes?

     

    External messages using Plus Addressing are flowing through our CES appliance fine, so yes, Exchange Online does respond to SMTP Call-Ahead correctly.

     

    4) How long after enabling Plus Addressing with Powershell should it take to function correctly?  I enabled it for my org 2 hours ago, and it is still not even functioning internally. (user mailbox to user mailbox within our own tenant)

     

    It took about 6 hours to finally start working.

  • stukeyPlus addressing does not offer disposable email addresses, but unique email addresses per recipient (based on the recipient address) that can be created without the hassle of going through IT. You can't delete, remove or disable them. It was never the goal of plus-addresses to offer disposable mail addresses. Your only option is to use rules to delete all incoming mails for specific plus-addresses you handed out.

  • stukey's avatar
    stukey
    Iron Contributor

    I can’t see a way to delete or remove a plus address. How do you do that, or is it not possible? Otherwise the usefulness of plus addresses is somewhat limited... you can’t use them as disposable email aliases for specific senders

  • mri503's avatar
    mri503
    Copper Contributor

    Is sending as a proxy address still in the works?

  • SyPatWork's avatar
    SyPatWork
    Copper Contributor

    It's a very nice feature, but I can't find the documentation for what will happen with addresses already containing + signs, after turning it on. 

  • That is great news and we're already evaluating to using it in our company.  It would be a great addition if we could change the character from a plus '+' to a custom character, e.g. the underscore '_', because many cloud services and web forms still do not accept the '+'-character as a valid character in an email address.

     

    https://office365.uservoice.com/forums/273493-office-365-admin/suggestions/41763787-allow-custom-characters-for-plus-addressing

  • Kam's avatar
    Kam
    Silver Contributor

    Doesn't this mean we can't use + symbols on our email addresses anymore because this is enabled?