ActionMailer not delivering mail when SMTP settings configured dynamically - ruby-on-rails

Question

I'm trying to set up ActionMailer's SMTP settings to be able to be configured at run time, but when that happens it doesn't seem to connect to the 3rd party service to deliver the mail. Below are 2 scenarios, the first of which the mail will send and deliver, the second of which nothing happens. I'm using the development environment for testing
This configuration is common to both scenarios
# config/environments/development.rb
config.action_mailer.perform_deliveries = true
config.action_mailer.raise_delivery_errors = false
config.action_mailer.default :charset => "utf-8"
config.action_mailer.delivery_method = :smtp
This works:
# config/environments/development.rb
config.action_mailer.default_url_options = { host: 'www.mysite.com' }
config.action_mailer.smtp_settings = {
:address => "smtp.thirdpartyservice.com",
:port => 587,
:domain => 'mysite.com',
:user_name => "me#mysite.com",
:password => "my-password",
:authentication => "plain",
:enable_starttls_auto => true
}
This delivers the mail, but also when tailing the logs, there is a slight delay in the request so I know the request is being made to the third party service.
This doesn't work:
This is the setup I want, using a custom mailer that I'm using.
class MyCustomMailer < Devise::Mailer
before_filter :use_smtp_settings
def example_mailer(record)
Rails.logger.warn self.smtp_settings
#resource = record
mail(to: record.email,
from: AppSettings.first.mailer_sender,
subject: "Example")
end
private
def use_smtp_settings
self.default_url_options[:host] = AppSettings.first.domain_address
self.smtp_settings = {
:address => AppSettings.first.smtp_address,
:port => AppSettings.first.smtp_port,
:domain => AppSettings.first.smtp_domain,
:user_name => AppSettings.first.smtp_username,
:password => AppSettings.first.smtp_password,
:authentication => "plain",
:enable_starttls_auto => true
}
end
end
The rails logger in the #example_mailer() method shows the same attributes that are used in the first example, albeit loaded from the app_settings table. However when tailing the logs this time, there is no delay so ActionMailer doesn't seem to even try making a request to the third party service.

Answer 1

This won't work because you're modifying the smtp settings on an instance of your mailer but the underlying mail gem reads it from the mailer class level attribute. The supported way to do this in Rails 4.0 and above is to pass a custom header called :delivery_method_options to the mail call, e.g:
class MyCustomMailer < Devise::Mailer
before_filter set_default_host
def example_mailer(record)
mail to: record.email,
from: app_mailer_sender,
subject: "Example",
delivery_method_options: app_smtp_settings
end
private
def app_settings
#app_settings || AppSettings.first
end
def app_domain_address
app_settings.domain_address
end
def app_mailer_sender
app_settings.mailer_sender
end
def app_smtp_settings
self.smtp_settings = {
address: app_settings.smtp_address,
port: app_settings.smtp_port,
domain: app_settings.smtp_domain,
user_name: app_settings.smtp_username,
password: app_settings.smtp_password,
authentication: "plain",
enable_starttls_auto: true
}
end
def set_default_host
default_url_options[:host] = app_settings.domain_address
end
end
end
One little tip - don't repeatedly call AppSettings.first since that re-queries the database (actually it'll be caught by the AR query cache but a new instance will be created every time). But you knew that right ;-)