Allow a user to change part of the development.rb

I am developing an email system that allows a user to send an email to another person. What I want a user to be able to do is be able to specify the email address that they send the email from - so at the minute an email gets sent from a generic email address that I have coded into development.rb as per below:

Rails.application.configure do

  config.cache_classes = false

  config.eager_load = false

  config.consider_all_requests_local       = true
  config.action_controller.perform_caching = false

  config.action_mailer.raise_delivery_errors = false

  config.active_support.deprecation = :log

  config.active_record.migration_error = :page_load
  config.assets.debug = true

  config.assets.digest = true

  config.assets.raise_runtime_errors = true

  config.action_mailer.delivery_method = :smtp
  config.action_mailer.smtp_settings = {
    address:              'smtp.gmail.com',
    port:                 587,
    domain:               'example.com',
    user_name:            'myemail@emailaddress.com', #replace with your username Eg. john.smith
    password:             'mypassword', #replace with your gmail password
    authentication:       'plain',
    enable_starttls_auto: true  }

end

So, depending on what a user enters on the form I want the development.rb to change so that the email can be sent from the user's account. I'm assuming that some kind of instance variable is necessary, but is this possible?

My form is as follows:

<%= form_for @email do |f| %>

  <% if @email.errors.any? %>
    <div id="error_explanation">
      <h2>
        <%= pluralize(@email.errors.count, "error") %> prohibited
        this email from being saved:
      </h2>
      <ul>
        <% @email.errors.full_messages.each do |msg| %>
          <li><%= msg %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <p>
    <%= f.label :address %><br>
    <%= f.text_field :address %>
  </p>
  <p>
    <%= f.label :port %><br>
    <%= f.text_field :port %>
  </p>
  <p>
    <%= f.label :domain %><br>
    <%= f.text_field :domain %>
  </p>

  <p>
    <%= f.label :user_name %><br>
    <%= f.text_field :user_name %>
  </p>

  <p>
    <%= f.label :password %><br>
    <%= f.text_field :password %>
  </p>
  <p>
    <%= f.label :authentication %><br>
    <%= f.text_field :authentication %>
  </p>
  <p>
    <%= f.label :bcc_address %><br>
    <%= f.text_field :bcc_address %>
  </p>

  <p>
    <%= f.label :enable_starttls_auto %><br>
    <%= f.text_field :enable_starttls_auto %>
  </p>
  <p>
    <%= f.label :cc_address %><br>
    <%= f.text_field :cc_address %>
  </p>
  <p>
    <%= f.label :bcc_address %><br>
    <%= f.text_field :bcc_address %>
  </p>

  <p>
    <%= f.label :title %><br>
    <%= f.text_field :title %>
  </p>

  <p>
    <%= f.label :text %><br>
    <%= f.text_area :text %>
  </p>

  <p>
    <%= f.submit %>
  </p>

<% end %>

My controller has the following:

def create
    @email = Email.new(email_params)
    if @email.save
        UserMailer.welcome_email(@email).deliver
        redirect_to @email
    else
        render 'new'
    end
end
private
    def email_params
        params.require(:email).permit(:address, :port, :domain, :user_name, :password, :authentication, :enable_starttls_auto, :to_address, :cc_address, :bcc_address, :title, :text)
    end

And my Mailer is:

class UserMailer < ApplicationMailer
  default from: 'no-reply@example.com'

  def welcome_email(email)
    @url  = 'http://localhost:3000/users/login'
    @email = email
    mail(to: @email.to_address, cc: @email.cc_address, bcc: @email.bcc_address, subject: @email.title)
  end
end

But is it possible for a user to enter their email details, and the system then use these in the development.rb file to send out the email?