[Dovecot] Check if a message has attachments

Hi all,

my question is not specific to Dovecot but to the IMAP protocol in general.

I'm working on a web based software that provides a simple webmail ( http://modoboa.org/). I'm wondering what would an efficient way to detect if a message (or a group of messages) has attachments. I know it certainly consists in checking for specific MIME constructions but how to achieve that without fetching the whole body for each message?

Thanks in advance,

Antoine Nguyen