Find and extract every email address from IMAP folder

file1.rb

chars = %w{ | / - \\ }
def find_all_email_addresses_in(base_folder)
  # Bash goodness :P
  a=`find #{base_folder} -type d -name cur`.split("\n") +`find #{base_folder} -type d -name new`.split("\n")
  @emails=[]
  # http://stackoverflow.com/questions/535644/find-email-addresses-in-large-data-stream
  a.each do |folder|
    Dir[folder+"/*"].each do |email|
      content = File.read(email)
      r1 = Regexp.new(/(((From|^To|Cc):.*<)\b[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}\b(>))/)
      r2 = Regexp.new(/\b[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}\b/)
      mails = content.scan(r1).join("\n").downcase
      @emails << mails.scan(r2).uniq
      @emails.flatten!.uniq!
    end
  end
  File.open(ENV['HOME']+"/emails.txt", 'w') {|f| f.write(@emails.sort.join(", ")) }
end

t = Thread.new { find_all_email_addresses_in(".") }

while t.alive?
  print chars[0]
  sleep 0.1
  print "\b"
  chars.push chars.shift
end

t.join
puts "Save all emails found to #{ENV['HOME']}/emails.txt"

Cool snippet. I add some features to generate an address book: https://gist.github.com/Mic92/7171933

This is for extracting from a local Maildir, not from IMAP, no?

And you'll (likely) want to make sure you're extracting from the headers only and not the body (stop at a blank line https://tools.ietf.org/html/rfc5322#page-7 ), and handle multiple comma-separated entries on a line.