Exchange Anonymous Relay

Despite the security implications sometime you have to allow Exchange to act as an Anonymous Relay. Some examples are when you need email notifications from devices like UPS or Backup System.

Configure Anonymous Relaying from the Exchange Management Shell

New-ReceiveConnector -Name AnonRelay-Local -usage Custom -Bindings 10.1.1.2:25 -fqdn exch-server.domain.com -RemoteIPRanges 10.1.1.100 -server EXCH-SERVER -permissiongroups AnonymousUsers

Get-ReceiveConnector AnonRelay-Local | Add-ADPermission -User “NT AUTHORITY\ANONYMOUS LOGON” -ExtendedRights “ms-Exch-SMTP-Accept-Any-Recipient”
Get-ReceiveConnector AnonRelay-Local | Add-ADPermission -User “NT AUTHORITY\ANONYMOUS LOGON” -ExtendedRights “ms-Exch-Bypass-Anti-Spam” 

Reference

http://blog.korteksolutions.com/how-to-enable-relaying-for-local-machines-or-devices-on-sbs-2008/