Ruby IMAP library: How can I show all messages in a folder?

Question

I need a script to fetch all my emails in all my folders and make a local backup of them together with attachments.here but it doesn't bring me further with listing all emails belongig to a folder. Also reading the RFC doesn't bring me much further.

When I issued

imap.list("", "*")

And

imap.examine("SomeFolder")

How can I use this to iterate over all emails of SomeFolder ?

And how would I further issue a query to get the messages as well as the associated attachments?

Answer 1

To get the UIDs of all emails in a mailbox, use imap.uid_search(["ALL"]). You can then fetch them all in RFC822 (.eml) format (which includes their attachments) like this:

require "net/imap"
require "mail"

# initialize your imap object here
imap = Net::IMAP.new(...)
imap.login(...)

imap.list("", "*").map(&:name).each do |mailbox|
    imap.examine(mailbox)

    # Create directory for mailbox backup
    Dir.mkdir(mailbox) unless Dir.exist? mailbox

    uids = imap.uid_search(["ALL"])
    uids.each_with_index do |uid, i|
        # fetch the email in RFC822 format
        raw_email = imap.uid_fetch(uid, "RFC822").first.attr["RFC822"]

        # use the "mail" gem to parse the raw email and extract some useful info
        email = Mail.new(raw_email)
        puts "[#{i+1}/#{uids.length}] Saving email #{mailbox}/#{uid} (#{email.subject.inspect} from #{email.from.first} at #{email.date})"

        # save the email to a file
        File.write(File.join(mailbox, "#{uid}.eml"), raw_email)
    end
end