Hello,

I found a solution to this problem. I simply needed to set the Account
again to let Outlook do what I want. The following way helped me out:

Public Function SendUsingRDO(ByRef Mailobject As Object)
Dim RDOSession As Redemption.RDOSession
Dim RDOMessage As Redemption.RDOMail
Dim RDOAccount As Redemption.RDOAccount

' save the mail, in case it is not saved until now
Mailobject.Save

Set RDOSession = CreateObject("Redemption.RDOSession")
RDOSession.MAPIOBJECT = Application.Session.MAPIOBJECT
Set RDOMessage = RDOSession.GetMessageFromID(Mailobject.EntryID)

Set RDOAccount = RDOMessage.Account ' get account

If Not RDOAccount Is Nothing Then
' set the account again
RDOMessage.Account = RDOSession.Accounts(RDOAccount.Name)
RDOMessage.Save
End If
RDOMessage.Send
SendUsingRDO = True
End Function

At first I read the Account that is used (reading). Upon this, I set
this value again (writing). Now calling the .Send method forces
Outlook to use the account that has been set but ignored. Strange...

Kukulkan