Cannot Send email with Exchange SMTP and WSUS Sync always Failed

I just purchase a WatchGuard Firebox Edge X10e like 2 weeks ago and I have 2 current issue that I currently encounter with this Firewall Applience.

Let me specify our Networking in my office first so that you can better understand my situation.

I have a Server that's run for Active Directory and Exchange under Microsoft Windows SBS 2003 R2 Premium Edition. Than I have 3Com Gigabit Switch and Linksys Wireless Access Point (this is for all Notebook  or mobile applience such as PDA users in the office). My Internet connection using ADSL Broadband and I'm using Prolink Hurricane ADSL Modem. So the network topology is as the attached Network Diagram.

And my problems are:

1. Email communication in our network is using MS Exchange 2003 with POP3 Connector to download email from our current mailserver. But to send email, we use the SMTP Server from Exchange. The problem we had here that when we try to send email with WatchGuard plug in our network, all email will not send. All email is sitting queue in the Exchange and with status failed. This problems occurs either i used DNS or Smart Host. But when I unplug the WatchGuard, all email can sent out fine without a problem with DNS or Smart Host.

As the result of this problem, I try to create the Firewall Policy to allow access to the Smart Host domain on port 25. And I try to send email again. But the problem is still exist. Checking the log, I found out that there is packet transaction to the Smart host and it's allow. But when i check my Smart Host statistic, there is no email coming thru.

May 5 13:40:33 kernel allow in eth0 150 tcp 20 40 63.208.196.179 125.162.249.92 25 25851 ack psh fin (default)

2. The second problem I had is with WSUS. We are using WSUS to distrubute updates for Server and Clients PCs. But when the SBS doing syncronization with Windows Update, the sync is failed and I got the following message.

WebException: The underlying connection was closed: An unexpected error occurred on a receive. ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
at System.Web.Services.Protocols.WebClientProtocol.GetWebResponse(WebRequest request)
at System.Web.Services.Protocols.HttpWebClientProtocol.GetWebResponse(WebRequest request)
at Microsoft.UpdateServices.ServerSync.ServerSyncCompressionProxy.GetWebResponse(WebRequest webRequest)
at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
at Microsoft.UpdateServices.ServerSyncWebServices.ServerSync.ServerSyncProxy.GetCookie(AuthorizationCookie[] authCookies, Cookie oldCookie, String protocolVersion)
at Microsoft.UpdateServices.ServerSync.ServerSyncLib.InternetGetServerCookie(ServerSyncProxy proxy, AuthorizationCookie[] authCookies, WebServiceCommunicationHelper webServiceHelper)
at Microsoft.UpdateServices.ServerSync.ServerSyncLib.Authenticate(AuthorizationManager authorizationManager, Boolean checkExpiration, ServerSyncProxy proxy, Cookie cookie, WebServiceCommunicationHelper webServiceHelper)
at Microsoft.UpdateSer

I have trying adding all domain name that WSUS used for sync to the allow list of domain name, but I still got the same result.

Does anyone can help me with this problems?Start Free Trial