Trying to write to a Property which was not opened with Mapi.Modify leads to conversations crash

[Frederick Roth]

using (var source = (IMessage) store.OpenEntry ([ENTRYID])) {
 source.SaveChanges ();
}

leads to:

39415 ERROR HttpHandler (null) - NMapi.MapiNetworkErrorException: 0x80040115: MAPI_E_NETWORK_ERROR: Network error or i/o error
  at NMapi.Properties.TeamXChangeMapiProp.SaveChanges (Int32 flags) [0x00043] in /home/froth/nmapi/providers/NMapi.Provider.TeamXChange/Properties/TeamXChangeMapiProp.cs:82

but should lead to:

NoAccess-Exception