问题
I want to process a bunch of my emails with Net::IMAP, but I want to skip the ones with attachments because they take too long. Any hints? Ultimately, I'm looking to download all the text and HTML content of emails, as fast as possible. Right now, I'm fetching one UID at a time, and parallelizing it with 15 processes (the max GMAIL allows), but I'm hitting a snag on the messages with attachments.
imap = Net::IMAP.new('imap.gmail.com', 993, usessl = true, certs = nil, verify = false)
imap.authenticate('XOAUTH2', user.email, user.token)
mailbox = "[Gmail]/All Mail"
imap.select(mailbox)
message_id = 177
imap.fetch(message_id,'RFC822')[0].attr['RFC822'] # this fetches the whole message, including attachment, which makes it slow...
回答1:
imap rfc does not provide any such implementations but as an alternative there could be a possible hack, assuming that the mail is following the rfc standard, fetch the entire mail header of mail and check for content type if it is multipart/mixed then for sure an attachment exists in a mail.
On content type you can get more info at http://en.wikipedia.org/wiki/MIME
This is just one of possible ways to find an attachment.
来源：https://stackoverflow.com/questions/15731920/is-it-possible-to-only-download-imap-messages-without-attachments