ReadHeader is a virtual procedure in TIdMessageDecoder that specifies the method used to read an RFC-2822 compliant message body. TIdMessageDecoder descendants, like TIdMessageDecoderMIME and TIdMessageDecoderUUE, must override ReadHeader to implement storage of parsed header names and values in message Headers. 

ReadHeader must also update PartType based on header values specific to the message decoder class. Additional properties in a descendant class may also require updates based on values detected in Header.

TIdMessageDecoderMIME 

TIdMessageDecoderUUE 

TIdMessageDecoderXXE 

TIdMessageDecoderQuotedPrintable 

TIdMessageDecoder.Headers 

TIdMessageDecoder.PartType