Reading emails using POP3 in Ruby
By: James Edward Gray II in Ruby Tutorials on 2009-03-03
This example retrieves messages from the server and deletes them on the server.
Messages are written to files named 'inbox/1", 'inbox/2", .- Replace 'pop.example.com" with your POP3 server address, and 'YourAccount" and 'YourPassword" with the appropriate account details.
require 'net/pop' pop = Net::POP3.new('pop.example.com') pop.start('YourAccount', 'YourPassword') # (1) if pop.mails.empty? puts 'No mail.' else i = 0 pop.each_mail do |m| # or "pop.mails.each ..." # (2) File.open("inbox/#{i}", 'w') do |f| f.write m.pop end m.delete i += 1 end puts "#{pop.mails.size} mails popped." end pop.finish # (3)
- Call Net::POP3#start and start POP session.
- Access messages by using POP3#each_mail and/or POP3#mails.
- Close POP session by calling POP3#finish or use the block form of start.
Shortened Code
The example above is very verbose. You can shorten the code by using some utility methods. First, the block form of Net::POP3.start can be used instead of POP3.new, POP3#start and POP3#finish.
require 'net/pop' Net::POP3.start('pop.example.com', 110, 'YourAccount', 'YourPassword') do |pop| if pop.mails.empty? puts 'No mail.' else i = 0 pop.each_mail do |m| # or "pop.mails.each ..." File.open("inbox/#{i}", 'w') do |f| f.write m.pop end m.delete i += 1 end puts "#{pop.mails.size} mails popped." end end
POP3#delete_all is an alternative for each_mail and delete.
require 'net/pop' Net::POP3.start('pop.example.com', 110, 'YourAccount', 'YourPassword') do |pop| if pop.mails.empty? puts 'No mail.' else i = 1 pop.delete_all do |m| File.open("inbox/#{i}", 'w') do |f| f.write m.pop end i += 1 end end end
And here is an even shorter example.
require 'net/pop' i = 0 Net::POP3.delete_all('pop.example.com', 110, 'YourAccount', 'YourPassword') do |m| File.open("inbox/#{i}", 'w') do |f| f.write m.pop end i += 1 end
Memory Space Issues
All the examples above get each message as one big string. This example avoids this.
require 'net/pop' i = 1 Net::POP3.delete_all('pop.example.com', 110, 'YourAccount', 'YourPassword') do |m| File.open("inbox/#{i}", 'w') do |f| m.pop do |chunk| # get a message little by little. f.write chunk end i += 1 end end
Using APOP
The net/pop library supports APOP authentication. To use APOP, use the Net::APOP class instead of the Net::POP3 class. You can use the utility method, Net::POP3.APOP(). For example:
require 'net/pop' # Use APOP authentication if $isapop == true pop = Net::POP3.APOP($is_apop).new('apop.example.com', 110) pop.start(YourAccount', 'YourPassword') do |pop| # Rest of the code is the same. end
Fetch Only Selected Mail Using 'UIDL" POP Command
If your POP server provides UIDL functionality, you can grab only selected mails from the POP server. e.g.
def need_pop?( id ) # determine if we need pop this mail... end Net::POP3.start('pop.example.com', 110, 'Your account', 'Your password') do |pop| pop.mails.select { |m| need_pop?(m.unique_id) }.each do |m| do_something(m.pop) end end
The POPMail#unique_id() method returns the unique-id of the message as a String. Normally the unique-id is a hash of the message.
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