Para deshabilitar y habilitar  POP e IMAP para todos los usuarios y usuario individual de Office 365, siga estos pasos:

1. Conectarse a Exchange Online:

Nos conectamos con derechos de Administrador.

$Credential = Get-Credential

$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri «https://ps.outlook.com/powershell» -Credential $Credential -Authentication Basic -AllowRedirection
$ImportResults = Import-PSSession $Session

2. Desactivar todos los buzones de usuarios de POP e IMAP:

$Mailboxes = Get-Mailbox -ResultSize Unlimited
ForEach ($Mailbox in $Mailboxes) {$Mailbox | Set-CASMailbox -PopEnabled $False -ImapEnabled $False }

Si queremos volver activar solo reemplazamos $False por $True .

$Mailboxes = Get-Mailbox -ResultSize Unlimited
ForEach ($Mailbox in $Mailboxes) {$Mailbox | Set-CASMailbox –PopEnabled $True –ImapEnable $True }

Si solamente queremos desactivar cuenta individual.

$Mailbox = Get-Mailbox -Identity «jcastaneda» -ResultSize Unlimited
ForEach ($Mailbox in $Mailbox) {$Mailbox | Set-CASMailbox -PopEnabled $False -ImapEnabled $False }

$Mailbox = Get-Mailbox -Identity «jcastaneda» -ResultSize Unlimited
ForEach ($Mailbox in $Mailbox) {$Mailbox | Set-CASMailbox -PopEnabled $True -ImapEnabled $True }

3. Cierre la sesión en línea de Exchange:
Remove-PSSession $Session