require 'net/imap'

imap = Net::IMAP.new('example.com')
imap.authenticate('LOGIN', 'mailaccount@example.com', 'password')
imap.select('INBOX')
if not imap.list('INBOX', 'testfolder')
  imap.create('INBOX.testfolder')
end
imap.uid_search(["FROM", "test@example.org"]).each do |message_id|
  puts(message_id)
  imap.uid_copy(message_id, "INBOX.testfolder")
  imap.uid_store(message_id, "+FLAGS", [:Deleted])
end
imap.expunge