IdMessage

TIdMIMEBoundary is a TObject descendant that implements a class used to detect and handle MIME boundary markers in message headers for an RFC 822-compliant message. 

In essence, TIdMIMEBoundary is used as a Stack-based container for MIME boundary markers detected in a "Content-Type" header. New boundary markers are added to the the top of the stack, using the Push method, when they are detected during header processing. 

Like any stack container, TIdMIMEBoundary also has mechanisms to Pop and Clear accumulated values in the boundary marker list. 

TIdMIMEBoundary also provides a class function to locate a boundary marker in a given string, FindBoundary, without requiring a realized instance of the class. 

TIdMIMEBoundary is the type used to represent the MIMEBoundary property in TIdMessage.

TIdMessage 

TIdMessage.MIMEBoundary 

IndySupport