
Introduction
Microsoft has provided option to enable plus addressing in office 365, It was a long awaited feature and was available in G Suite for long time.
This feature helps to give different email addresses in signing up for newslettters etc and you can easily configure your inbox to route emails to correct folder.
What to consider before change ?
- Find list of email address currently have aliases with +tag, Remove them before the change and once it is replicated, then enable setting. Microsoft said the existing such addresses could face issue.
- If you have 3rd party email gateway, Make sure to enable + addressing there first to get emails to your office 365 mailbox.
- If you have internal smtp relay or on-prem exchange, please note that it may not be supported there and you may want to
- fyi, You can’t use +tag in From Field.
- This change could take longer to replicate within Office 365, It took 1.5 hours, so you might want to communicate accordingly.
Implementation
- Enable in Office 365
- Connect to Exchange Online using Global Admin Credentials :
Set-OrganizationConfig -AllowPlusAddressInRecipients $true
- Enable in 3rd Party Email Gateway
- Proofpoint has subaddressing feature.
- Cisco Email Security has sievechar command to enable + addressing.
Send some emails from your Gmail, Hotmail to verify it works, if you receive emails which means it worked and you can notify your end users to leverage this feature.

FYI, If you send email to another recipient within your org, it will still tell you that address is invalid but email will still be delivered.
Thanks for reading !