By default, it takes between 24 to 48 hours for Exchange Online to re-synchronize the address lists and all users to download the most updated information. Unfortunately, the commands available in Exchange on premise to update the Address Lists are not available in Office365 – Exchange Online.
https://technet.microsoft.com/en-us/library/aa997982(v=exchg.160).aspx
Therefore we will need to force that sync manually. Updating the Address Lists, requires requires to have the Address List Management Role. By default in Exchange online, the Address List role isn’t assigned to any role groups.
1 – Connect to Exchange Online
$UserCredential = Get-Credential $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection Import-PSSession $Session
2 – Create a new Group Role
New-RoleGroup -Name "AddressList" -Roles "Address Lists" -Members Account@domain.com
3 – Run the Following Commands to update the lists
Get-AddressList Set-AddressList -Identity "All users"
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