How to send emails with multiple, dynamic smtp using Actionmailer/Ruby on Rails

Question

I saw this post but mine is slightly different:

Rails ActionMailer with multiple SMTP servers

I am allowing the users to send mail using their own SMTP crede

Answer 1

Since Rails 4+ it works to give the credentials directly via the delivery_method_options parameter:

class UserMailer < ApplicationMailer
  def welcome_email
    @user = params[:user]
    @url  = user_url(@user)
    delivery_options = { user_name: params[:company].smtp_user,
                         password: params[:company].smtp_password,
                         address: params[:company].smtp_host }
    mail(to: @user.email,
         subject: "Please see the Terms and Conditions attached",
         delivery_method_options: delivery_options)
  end
end

See Sending Emails with Dynamic Delivery Options (Rails Guides)