MS Office365:Set mailbox size limits for a single user

$UserCredential = Get-Credential

$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection

Import-PSSession $Session

Set-Mailbox <userid> -ProhibitSendQuota 4.8GB -ProhibitSendReceiveQuota 5GB -IssueWarningQuota 4.7GB

Remove-PSSession $Session