Mails are not being sent

Hello I would be grateful if someone can help me step by step tp resolve this issue. I have my application on production environment. I define the SMTP server settings on config/environments/production.rb

as follows: config.action_mailer.raise_delivery_errors = true config.action_mailer.delivery_method = :sendmail ActionMailer::Base.default_url_options[:host] = ''

and nothing defined in my environment.rb related to the mails sending, except the sender email as follow: DEFAULT_MAILER = ""

When I trail the error log production.log, the log says that my emails are sent successfully on production. But the emails are not sending. How can I figure out what the problem is.

Your quick response is highly appreciated.

Thanks alot.