Forwarding Relay denied

Question / Problem

I get an error message "Relaying denied /Not allowed to relay" when using the action "Send auto reply to sender with following text", what can I do?

Answer / Solution

This error message means that  SmartPOP2Exchange tries to send out a message through the Exchange Server but the Exchange Server doesn't allow this.
To enable this please try the following:
The relaying permission for Exchange Server 2007/2010 and 2013 needs to be set using exchange powershell:
 Get-ReceiveConnector "<you receiveconnector id/name>" | Add-ADPermission -User "NT AUTHORITY\ANONYMOUS LOGON" -ExtendedRights "Ms-Exch-SMTP-Accept-Any-Recipient"
[See Help article at Microsoft]
Restricting the receive connector to localhost only is not possible; you need to accept at least the local network too: 127.0.0.0/8 (loopback) and 192.168.0.0/16