Plus Addressing Now Available in Exchange Online

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. 

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.

ajc196 Thank you for circling back with the answers you found.

Support for Groups and DL is being added and should be available in December. 

Andres-Bohren The time that the setting takes to permeate through the service differs but it should be in the region of hours, not days. If it is still not working, I would advise you to contact support to help diagnose the issue. 

SyPatWork Kam We are updating the documentation to be more specific about the expected behaviour. If Exchange Online can resolve the existing address with the plus, then it will be delivered as normal. The problem comes in for mailboxes on-premises that Exchange Online does not know about and message are being blindly routing messages via connector to the mailbox. In such a case, we will assume that the message is a plus address and strip out the plus and tag and deliver it to the parsed address.

DanielNiccoli Custom characters for sub-addressing is not something we have any intention to implement in the foreseeable future.

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

Hi Sean_Stevenson 

Thank you for the Link. Can't find "Hybrid" or "Synced" mentioned there.

Tried it for a CloudOnly Account in a Hybrid Environement. Also here Plus addressing to itself (onmicrosoft.com Address) did not work. But that should work right?

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

Is sending as a proxy address still in the works?

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

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.

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