Internet Direct (Indy) Version 9.0.1 Beta
TIdMessagePart.BoundaryBegin
Indicates that a boundary marker appears at the beginning of the message part.

property BoundaryBegin: Boolean;
Description
BoundaryBegin is a Boolean property that indicates that a boundary marker appears at the beginning of the message part. BoundaryBegin is used and updated when the message part is received by a message client.