Question : Problems sending email from iPhone configured with Active Sync

Exchange 2003 SP2
iPhone and iPad with iOS3
I'm able to add users on their iPhones but unable to send from some accounts
Some accounts display all folders and can send but some display only inbox but when trying to send it says "Cannot Send Email"

Exchange Application log has some OMA errors

Event Type:      Error
Event Source:      MSExchangeOMA
Event Category:      (1000)
Event ID:      1503
Date:            7/9/2010
Time:            3:46:44 PM
User:            N/A
Computer:      mailserver
Description:
An unknown error occurred while processing the current request:
Message: Value cannot be null.
Parameter name: assemblyString
Source: mscorlib
Stack trace:
   at System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark)
   at System.Reflection.Assembly.Load(String assemblyString)
   at Microsoft.Exchange.OMA.UserInterface.Global.Session_Start(Object sender, EventArgs e)

Message: Exception of type Microsoft.Exchange.OMA.DataProviderInterface.ProviderException was thrown.
EventMessage:
UserMessage: A System error has occurred while processing your request. Please try again. If the problem persists, contact your administrator.
Source: Microsoft.Exchange.OMA.UserInterface
Stack trace:
   at Microsoft.Exchange.OMA.UserInterface.Global.Session_Start(Object sender, EventArgs e)
   at System.Web.SessionState.SessionStateModule.RaiseOnStart(EventArgs e)
   at System.Web.SessionState.SessionStateModule.CompleteAcquireState()
   at System.Web.SessionState.SessionStateModule.BeginAcquireState(Object source, EventArgs e, AsyncCallback cb, Object extraData)
   at System.Web.AsyncEventExecutionStep.System.Web.HttpApplication+IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)


and

Event Type:      Error
Event Source:      Server ActiveSync
Event Category:      None
Event ID:      3005
Date:            7/9/2010
Time:            3:55:18 PM
User:            domain\btest
Computer:      mailserver
Description:
Unexpected Exchange mailbox Server error: Server: [mailserver.domain.local] User: [[email protected]] HTTP status code: [409]. Verify that the Exchange mailbox Server is working correctly.

I wish it would not work at all, but it works for some users

Thanks for any help

Answer : Problems sending email from iPhone configured with Active Sync

Just to clarify...did you really want to say 192.168.1.12-192.168.11.20   or did you mean 192.168.1.12-192.168.1.20

You should be able to go to Adminstrative Tools, Routing and Remote Access,  

In the left window right click on the Server Name > Properties > Click on the IP tab

Change from Dynamic to Static and enter in the address range you want to use.