If i backup my Macbook hard drive (thus including all Mail data/my imap mail account) does this backup include ALL the data stored at my imap mail server? Or w

If i backup my Macbook hard drive (thus including all Mail data/my imap mail account) does this backup include ALL the data stored at my imap mail server? Or would i be missing certain parts, like attachments or whatever? Would OfflineIMAP download 'more' data than i already have backed up?