Exchange Mailbox Does Not Exist For Business Standard User

We upgraded a user's license from Microsoft 365 Business Basic to Microsoft 365 Business Standard. We then got a report of failed delivery attempts when others emailed this user.

The status code for the failed delivery is 550 5.1.10 "This error occurs because the sender sent a message to an email address hosted by Office 365 but the address is incorrect or doesn't exist at the destination domain."

When I select the user's Mail tab in admin.microsoft.com it says the user doesn't have an Exchange Online license.

But on the Licenses and apps tab we can see the Standard license.

The user does not have a mailbox in the Exchange admin center.

I created a new test user and gave it the Business Basic license. Email works and the test user has the expected mailbox permissions settings under the mail tab as well as existing in the exchange admin center.

I'm continuing researching this but I'm not sure what could be going on here. Any suggestions would be appreciated.

Thanks.

Microsoft 365Exchange

Last Comment

DEMAN-BARCELO (MVP) Thierry

8/22/2022 - Mon

David Johnson, CD

12/20/2021

We upgraded a user's license from Microsoft 365 Business Basic to Microsoft 365 Business Standard

How?

What you should have done is buy a new business standard license and move the user from Business Basic to Business Standard.
Sounds like the user is in a new tenant

Vasil Michev (MVP)

12/20/2021

Did you first unassign the existing license? If so, the mailbox got (temporarily) disconnected and will be available after a while. The correct way to switch licenses would be to do it in a single operation, remove the old and add the new without confirming the changes in between.
Other than that, check the status of the Exchange service for the user, and for any provisioning errors (Get-MsolUser -HasErrorsOnly). A check via Get-Mailbox also wouldn't hurt.

ASKER CERTIFIED SOLUTION

DEMAN-BARCELO (MVP) Thierry

12/21/2021

THIS SOLUTION ONLY AVAILABLE TO MEMBERS.

View this solution by signing up for a free trial.

Members can start a 7-Day free trial and enjoy unlimited access to the platform.

See Pricing Options

Start Free Trial

GET A PERSONALIZED SOLUTION

Ask your own question & get feedback from real experts

Find out why thousands trust the EE community with their toughest problems.

Experts Exchange has (a) saved my job multiple times, (b) saved me hours, days, and even weeks of work, and often (c) makes me look like a superhero! This place is MAGIC!

Walt Forbes