Mailing Through Exchange webservice (VB.NET) - web-services

Question

Anyone here who has experience with using Exchange webservice.
I am trying to send an e-mail to myself using the webservice. This e-mail has another address as Sender, but it keeps taking my recipients e-mail address as Sender instead :s
This is my code:
Dim Message As MessageType = New MessageType()
Message.Subject = txt
Message.Body = New BodyType()
Message.Body.Value = ActiesOverzicht
Message.Sender = New SingleRecipientType
Message.Sender.Item = New EmailAddressType
Message.Sender.Item.EmailAddress = SenderEmail
Message.ToRecipients = New EmailAddressType(0) {}
Message.ToRecipients(0) = New EmailAddressType()
Message.ToRecipients(0).EmailAddress = RecipientsEmail
Message.Sensitivity = SensitivityChoicesType.Normal
this message goes into a list and is send with the following Code:
Public Sub SendMailToOperator(messageList As List(Of MessageType), esb As ExchangeServiceBinding)
' Create the CreateItem request.
Dim createEmailRequest As New CreateItemType()
' Specifiy how the e-mail will be handled.
createEmailRequest.MessageDisposition = MessageDispositionType.SendOnly
createEmailRequest.MessageDispositionSpecified = True
' Create the array of items.
createEmailRequest.Items = New NonEmptyArrayOfAllItemsType()
' Add the message to the array of items to be created.
createEmailRequest.Items.Items = messageList.ToArray()
'createEmailRequest.Items.Items(0) = Message
' Send a CreateItem request and get the CreateItem
' response.
Dim createItemResponse As CreateItemResponseType = esb.CreateItem(createEmailRequest)
End Sub
Does anyone have any Idea on how to solve this problem? Or what causes it?

Answer 1

AFAIK Exchange will normally always set the sender to the identity of the person logged in.
There are several ways around this, the easiest one being not using Exchange. Just send mail trough 'normal' SMTP.
If you have to use Exchange you should log in as the sender you're trying to use, or set up the permissions for the account you are trying to use as sender. The sender you're using should allow the account you use to login to send mail on it's behalf. The permissions can be changed through outlook.
There might also be a way to relax this restriction on the Exchange server, but I'm not an Exchange admin so I don't know how.