Need Additional Information in headers about mailkit

[jstedfast]

A1. Short answer: You can't. You can sort of guess based on whether or not the Content-Type header is a multipart or not, but you can't actually know if it contains attachments or not because that information is only available in the headers for each MIME part which cannot be fetched via POP3 without fetching the entire message.

A2. There's no way to do that. The POP3 protocol does not support this at all. The POP3 protocol only gives you 2 commands to work with: TOP which downloads headers + X number of lines after the headers and RETR which downloads the entire message.

With IMAP, you can download individual parts and get the MIME structure w/o having to download the entire message, so you might want to look into using IMAP instead.