constructor Create(
    Collection: TIdMessageParts; 
    const CopyFrom: TIdStream
); overload; reintroduce;

Create is an overloaded reintroduced constructor for the object instance. 

Create calls the inherited constructor using Collection as the owner for the memory-based message attachment. 

CopyFrom is the TIdStream instance with the content for the memory-based message attachment. Values in CopyFrom are read into the TIdMemoryStream instance allocated to the DataStream property. Values in CopyFrom stream are read into the DataStream property until the entire contents of the CopyFrom stream has been loaded in the DataStream property. 

Use an overloaded variant of the constructor to load the contents of the memory-based attachment from a String value.