Powershell Script referenced by http://behind-monitor.blogspot.com/ This Script creates a user in the domain and creates a mailbox. The mailbox is getting configured to receive into the inbox and forward mails to the user's private mail address. Exchange is getting configured to allow automatic forwarding to external addresses.

NewMailboxWithForwarding.ps1

<#
.SYNOPSIS
    This Script creates a user which gets the mails into his company mailbox (contoso.com) and also to his private mailbox (example.com).
.DESCRIPTION
    This Script creates a user in the domain and creates a mailbox.
    The mailbox is getting configured to receive into the inbox and forward mails to the user's private mail address.
    Exchange is getting configured to allow automatic forwarding to external addresses.
.NOTES
    FileName         : NewMailboxWithForwarding.ps1
    Version          : 1.0
    Author           : Daniel Müller (chdanielmueller)
    Last modified by : Daniel Müller (chdanielmueller)
.EXAMPLE
    Psh> NewMailboxWithForwarding.ps1
#>

 
## Start Script

# Ask for password and create user with mailbox
$password = Read-Host "Enter password" -AsSecureString
New-Mailbox -UserPrincipalName markus.muster@contoso.com -Alias markus.muster -Database "Mailbox Database 1" -Name "Markus Muster" -OrganizationalUnit Users -Password $password -FirstName Markus -LastName Muster -DisplayName "Markus Muster"

# Configure mailbox to receive and forward mails
Set-Mailbox -Identity "Markus Muster" -ForwardingSmtpAddress "markus.muster@example.com" -DeliverToMailboxAndForward $true

# Check and configure Microsoft Exchange to allow automatic forwarding to external addresses
Get-RemoteDomain Default | fl AutoForwardEnabled
Set-RemoteDomain Default –AutoForwardEnabled $true

## End Script