Another rails mailer not working issue - ruby-on-rails

Question

First in my project, I can receive the registration confirmation email sent by devise gem and mandrill service. So I assume my email config settings are correct. However, my own send_mail function just cannot send email successfully.
My mailer settings:
config.action_mailer.smtp_settings = {
address: "smtp.mandrillapp.com",
port: 587,
domain: Rails.application.secrets.domain_name,
authentication: "plain",
enable_starttls_auto: true,
user_name: Rails.application.secrets.email_provider_username,
password: Rails.application.secrets.email_provider_password
}
# ActionMailer Config
config.action_mailer.default_url_options = { :host => 'localhost:3000' }
config.action_controller.asset_host = 'localhost:3000'
config.action_mailer.asset_host = 'http://localhost:3000'
config.action_mailer.delivery_method = :smtp
config.action_mailer.raise_delivery_errors = true
# Send email in development mode?
config.action_mailer.perform_deliveries = true
Mailer Class:
class BidMailer < ActionMailer::Base
default from: "service#xxx.com"
def send_mail(bid)
#bid = bid
mail(to: 'xxxxx#gmail.com', subject: 'Bid Accepted', reply_to: 'service#xxx.com')
end
end
In the controller I simply call BidMailer.send_mail(bid).deliver. I also have the html file for in the view for the email body.
I can see this in my server console log:
Sent mail to xxx#gmail.com (24.0ms)
Date: Wed, 11 Mar 2015 22:39:45 +1100
From: service#xxx.com
Reply-To: service#xxx.com
To: xxx#gmail.com
Message-ID: <550029815f07_782a3fec29fa23c8413c#Shanes-MacBook-Pro.local.mail>
Subject: Bid Accepted
Mime-Version: 1.0
Content-Type: text/html;
charset=UTF-8
Content-Transfer-Encoding: 7bit
And also I can see similar email log when devise sends out registration confirm email.
But I totally dont get why I cannot get any email sent by my send_mail function?
Anyone could give some help? Thanks heaps!