Bulk Update Regional and Time Zone Settings for Exchange Online Mailboxes

I have been asked a few times by end users why the time and date are displayed incorrectly when they are using Outlook.

The most common reason is that when they first logged into Office 365 they managed to set the wrong time zone and regional settings. Having changed this a few times and explaining to the user what had happened I decided to look at updating this for all users in bulk.

This is easily achievable using PowerShell to configure your online Exchange environment. The method for connecting to your online Exchange via PowerShell depends if you have MFA configured for the user you are going to use to make the connection.

If you don’t have MFA configured, you need to follow these instructions.

If you do have MFA configured, you need to follow these instructions.

Once you are connected to your environment you can run the following command to see the current state of all users’ regional settings:

Get-Mailbox -ResultSize Unlimited | Get-MailboxRegionalConfiguration

These commands can take a long time to run due to resources restrictions that are put in place on the other end.

Providing you want all users to have the same regional settings you can run the following command with your chosen regional values:

There is a whole list here of different language codes and time zones that can be used.

Get-Mailbox | Set-MailboxRegionalConfiguration -Language 2057 -TimeZone "GMT Standard Time"

Once this has finished you can re-run the first command to verify it has taken effect:

This will only affect your current users. Newly created users will need to set their regional settings manually as before.