Use TMail -> Mail gem in Rails 2.3

action_mailer_no_tmail.rb

require 'action_mailer'
require 'mail'

module ActionMailer
  class Base
    
    def clean_address(str)
      EmailAddress.parse(str, :no_default_name => true).quoted rescue str
    end
    
    def create_mail
      m = Mail.new

      m.charset  = charset
      m.subject  = subject
      m.to       = clean_address(recipients)
      m.from     = clean_address(from)
      m.bcc      = bcc unless bcc.nil?
      m.cc       = cc unless cc.nil?
      m.reply_to = reply_to unless reply_to.nil?
      
      m.mime_version = mime_version    unless mime_version.nil?
      m.date         = sent_on.to_time rescue sent_on if sent_on
      m.message_id   = "<#{Mail.random_tag}@yourdomain.com>"

      headers.each { |k, v| m[k] = v }
      
      if @parts.empty?
        raise "JonathanActionMailer: Not supported -- empty parts"
      else
        if String === body
          raise "JonathanActionMailer: Not supported -- string body"
        end

        @parts.each do |p|
          part = (Mail::Part === p ? p : p.to_mail(self))
          m.add_part(part)
        end

        m.content_type(["multipart", "alternative", m.content_type_parameters])
      end
      
      @mail = m
    end
  end
  
  class Part
    def to_mail(defaults)
      real_content_type, ctype_attrs = parse_content_type(defaults)
      part = Mail::Part.new(:content_type => real_content_type, :content_disposition => "inline", :body => body, :charset => "utf-8")
      
      raise "JonathanActionMailer: Not supported -- @parts not empty" unless @parts.empty?
      raise "JonathanActionMailer: Not supported -- transfer_encoding: base64" if (transfer_encoding || "").downcase == "base64"
      raise "JonathanActionMailer: Not supported -- attachments" if content_disposition == "attachment"
      raise "JonathanActionMailer: Not supported -- headers on parts" if headers.any?
      
      part
    end
  end
end

module Mail
  class Message
    def ready_to_send
      nil
    end
  end
end

Thanks for posting these!