The ReadFromFile method loads the value of a string or binary field from a file.
objField.ReadFromFile(fileName)
The ReadFromFile method reads the string or binary value from the specified file and stores it as the value of the Field object. It replaces any previously existing value for the field.
ReadFromFile is not supported for simple types, such as vbInteger, vbLong, and vbBoolean. Microsoft® Visual Basic® provides common functions to read and write these base types to and from files. The ReadFromFile method fails if the Type property of the Field object is not vbString or vbBlob.
MAPI properties of type PT_BINARY are read from persistent storage in counted binary format but converted to a hexadecimal string format when they are stored as Field values. Comparison operations on the Value property and the actual contents of the file can return "not equal" even when the values are equivalent.
In addition, support for types can vary among providers. Not all providers support both the vbString and vbBlob property types.
ReadFromFile returns CdoE_INTERFACE_NOT_SUPPORTED for Field objects obtained from a Folder object's Fields collection.
WriteToFile Method (Field Object)