Internet Direct (Indy) Version 9.0.2 Beta
TIdMessageParts.RelatedPartCount
Indicates the number of attachments in the message part collection.

property RelatedPartCount: integer;
Description
RelatedPartCount is a read-only Integer property that identifies the number of attachments in the message parts collection. RelatedPartCount is updated in TIdMessage.GenerateHeader, and indicates the number of TIdAttachment items that contain a Content-Id header in the ExtraHeaders property. Attachments without a Content-Id are included in AttachmentCount.