Set Time Zone for the mailbox with Powershell

Open Powershell As Administrator and connect to Office365  

Set Time Zone for a Mailbox:

Set-MailboxRegionalConfiguration <Identity> -TimeZone <"Time Zone"> 

Example:

Set-MailboxRegionalConfiguration yourmailbox -TimeZone "Pacific Standard Time" 

Set Time Zone + Language for a Mailbox:

Set-MailboxRegionalConfiguration <Identity> -TimeZone <"Time Zone"> –Language <Language Code> 

Example:

Set-MailboxRegionalConfiguration yourmailbox -TimeZone "Pacific Standard Time" –Language en-US  

Display information about Time Zone and Language for a specific user:

Get-MailboxRegionalConfiguration <Identity> 

Example:

Get-MailboxRegionalConfiguration yourmailbox

Display Time zone and Language settings for all users:

$Users = Get-Mailbox -ResultSize unlimited -Filter {(RecipientTypeDetails -eq 'UserMailbox')} $Users | Get-MailboxRegionalConfiguration