[Dovecot] Getting the SMTP envelope through IMAP?

Hi,

just a simple question about dovecot:

The mbox file format contains the SMTP envelope sender and transmission date in a FROM ... line preceding the RFC822 mail header and body.

As far as I see at the moment, the IMAP protocol does not support transmission of that SMTP envelope data in either way, but confusingly uses the term „envelope” for a structure describing the RFC822 mail header.

My question is, whether there is any way to retrieve the SMTP envelope through dovecot's IMAP anyway, maybe through some extension.

regards Hadmut