无法使用cram_md5身份验证通过SMTP通过SMTP发送电子邮件

Question

I am writing a Ruby script to send email using the 'mail' gem.

These are my SMTP settings on my local machine:

mailer_options:
  address: smtp.gmail.com
  port: 465
  domain: gmail.com
  user_name: example@gmail.com
  password: example_password
  authentication: :cram_md5
  enable_starttls_auto: true
  ssl: true

When I try to send email with the above SMTP settings, I get the following exception:

/opt/rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/net/smtp.rb:968:in `check_auth_continue': 504 5.7.4 Unrecognized Authentication Type ka3sm12016635pbc.32 - gsmtp (Net::SMTPSyntaxError)from /opt/rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/net/smtp.rb:758:in `block in auth_cram_md5from /opt/rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/net/smtp.rb:941:in `critical'
from /opt/rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/net/smtp.rb:756:in `auth_cram_md5'
from /opt/rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/net/smtp.rb:731:in `authenticate'
from /opt/rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/net/smtp.rb:566:in `do_start'
from /opt/rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/net/smtp.rb:519:in `start'
from /opt/rtpg/vendor/bundle/ruby/2.0.0/gems/mail-2.5.4/lib/mail/network/delivery_methods/smtp.rb:112:in `deliver!'
from /opt/rtpg/vendor/bundle/ruby/2.0.0/gems/mail-2.5.4/lib/mail/message.rb:2129:in `do_delivery'
from /opt/rtpg/vendor/bundle/ruby/2.0.0/gems/mail-2.5.4/lib/mail/message.rb:234:in `deliver'
from /opt/rtpg/vendor/bundle/ruby/2.0.0/gems/mail-2.5.4/lib/mail/mail.rb:140:in `deliver'

I tried searching for this error and found

SASL LOGIN authentication failed: Invalid authentication mechanism on Rails using Postfix and Dovecot on Ubuntu 12.10

but it does not help.

Answer 1

Why are you using MD5? If you're using TLS (SSL) you won't need to do this because the connection itself is encrypted and even a Base64 encoded password is secure.

When you connect to a server it will advertise what authentication types are allowed. In the case of Google Gmail the header looks like:

250-AUTH LOGIN PLAIN XOAUTH XOAUTH2 PLAIN-CLIENTTOKEN

CRAM-MD5 is not supported. All the others are.

Google's probably dropped MD5 because that method provides little in the way of security given how easily cracked MD5 is.

Answer 2

You won't be able to authenticate to Gmail using cram_md5 . Here is an example configuration for using Gmail:

Mail.defaults do
  delivery_method :smtp, { 
    :address => 'smtp.gmail.com',
    :port => '587',
    :user_name => ENV['GMAIL_SMTP_USER'],
    :password => ENV['GMAIL_SMTP_PASSWORD'],
    :authentication => :plain,
    :enable_starttls_auto => true
  }
end

Source: https://github.com/mikel/mail/wiki/Sending-email-via-Gmail-SMTP