GetHeader is a procedure used to extract Header values for a message, and store the header value in
TIdMessage properties. GetHeader updates the following properties from their associated message header:
- ContentType
- ContentTransferEncoding
- Subject
- From
- MsgId
- Newsgroups
- Recipients
- CCList
- Organization
- ReceiptRecipient
- References
- ReplyTo
- Date
- Sender
- Priority