To choose from multiple email address while sending mail

  I want the user to have the facility to choose from which of his email
address he wants to send the mail.

example a user may wish to send mail from or or from some other email address.
How do i configure action mailer seetings to handle this.
MY current actionmailer settings as follows allow me to send mail only
from one email address.

config.action_mailer.raise_delivery_errors = true

#set delivery method to :smtp, :sendmail or :test
config.action_mailer.delivery_method = :smtp

#these options are only needed if you choose smtp delivery
config.action_mailer.smtp_settings = {
  :address => "",
  #:domain =>'',
  :port => 25,
  :authentication => :login,
  :user_name => Username goes here,
  :password => password goes here


Please help

And Also i believe for sending email through gmail tls is required. So
how should i go about it also.

Thank you