Gmail allows users to create custom email addresses on the fly by appending "+keyword" to their email address.
So, "myaddy@gmail.com" and "myaddy+something@gmail.com" & "myaddy+somethingelse@gmail.com" all point at the same account (myaddy@gmail.com).
Is there a (reasonably simple) way to configure MS Exchange (any version) to behave similarly?
Bonus: is there an official term for this feature?
It's called "SMTP Tags" or "sub addressing" depending on who you speak to. You may find this wikipedia article useful as it talks about this feature in email.
As a practical matter it isn't supported by quite a few email systems for various reasons - some good (or at least understandable), some not so good. If you use it as an anti-spam mechanism (e.g. to track who gives your address away) then be warned that spammers are smart enough to remove these parts from a list of email addresses...
IIRC, exchange doesn't support it and doesn't really have a mechanism for doing so (you could of course add multiple SMTP addresses to a user's mailbox to create a similar effect but this is obviously very inconvenient to set-up and maintain for all concerned).
This feature is now available on Office 365 Exchange!
Exchange admins will have to enable this manually on their server. This can be done through Powershell using the following command:
Set-OrganizationConfig -AllowPlusAddressInRecipients $true
For instructions on how to use Powershell, you can find out more here: https://docs.microsoft.com/en-us/powershell/exchange/exchange-online-powershell-v2?view=exchange-ps
The setting may not instantly take effect so please expect a delay before you can start using plus addresses.
We're still waiting documentation on this feature and from feedback I've seen, it doesn't work for everyone currently.
TIP: After seeing some feedback, I've done some testing and concluded that this feature may not function correctly on hybrid exchange servers.
Exchange doesn't have the ability to do this. The address is used as a lookup for recipient mail, which is checked against the address lists stored in the system. A new address would have to be added for each tag you use, which is not long term supportable.
However, there are hooks for third party utilities to provide this functionality. The hooks that AntiVirus/AntiSpam systems use, Transport Agents, could be leveraged by such a utility to strip off the information after the + and add it to a mail header, or whatever needs to be done to it. This would allow delivery of the mail to the end user as the To: address would be correctly formatted for Exchange.
I don't know of any packages that do this, though.
I know it's been a long time since originally asked, but this post is still high on Google search results and appears to still be a commonly asked question. So, for those who are curious... although Outlook.com (previously Hotmail) has supported it since 2013, Exchange & O365 doesn't officially support subaddressing per RFC 5233 (at least not as of 2019). However, you may consider the ever fun task of setting up transport rules which allow you to effectively achieve the same thing as described in this blog...
https://durdle.com/2015/01/11/office-365-email-suffix-matching/
If you want to see it officially supported, you may consider upvoting the request that was started in 2017 to support RFC 5233...
With enough scripting time and knowledge, you should be able to put something together with the "catchall" mailbox sink for Exchange Server
http://support.microsoft.com/Default.aspx?kbid=324021
Sounds like you could add a new email alias to your all of your users like @domain.local Apparently the catchall won't let you forward email to the same domain, to avoid loops.
Then, in the catchall, anything with a "+" sign (or any other criteria) could be re-routed to the user address in the domain.local domain - you might even be able to take that tag and insert it into the subject.
So "myaddy+something@domain.com" gets forwarded myaddy@domain.local
Haven't done it, but looks like it's possible depending on how much work you want to put into it.
it seems that office 365 and exchange now support it : According to microsoft website (see link below)
From September 2020, plus addressing, also known as subaddressing, is available in Exchange Online. Subaddressing is a defined way to support dynamic, disposable recipient (not sender) email addresses for mailboxes.
An SMTP email address uses the basic syntax: @. For example, sean@contoso.com.
Plus addressing uses the syntax: +@. For example, sean+newsletter@contoso.com.
The original email address must be valid; the +tag value that you add is arbitrary, although regular character restrictions for SMTP email addresses apply (for example, no spaces). For more information about using plus addresses, see Using plus addresses.
Plus addressing is available in Outlook. By default, plus addressing support is disabled in Exchange Online. Since Exchange Online has always supported regular email addresses that already contain the plus sign, if you enable plus addressing, these email addresses might stop working.
If your organization's email is routed through Exchange Online to your on-premises servers, mailboxes hosted on-premises will also be able to use plus addresses.
Use the new Exchange admin center to enable plus addressing In the new Exchange admin center, go to Settings > Mail flow.
Select Turn on plus addressing for your organization, and then select Save.
As of 2022 and Exchange 2019, sub-addressing/plus-addressing is still not supported in Exchange on-premises. There is a third-party tool called QSS Exchange Custom Sender which provides this functionality for on-premises Exchange 2013/2016/2019 via a Transport Agent.
