如何区分莲花笔记中的电子邮件和聊天文档

I'm trying to extract all emails and chat history of a person from his nsf file (lotus notes). I'm using Notes.jar. All the entries in nsf files are documents. Is there a way to identify which document is email and which document is chat. There is an item named "Form" which is used to identify mails (memo), meeting invites (appointment). The problem I face here is both email and chat has form type "Memo". Kindly suggest me a way to differentiate between email and chat.I'm trying to extract all emails and chat histo