Send email confirmation when BTC payment is confirmed

app/mailers/notification_mailer.rb

@@ -23,4 +23,11 @@ class NotificationMailer < ApplicationMailer
     @subject = "New invitations added to your account"
     mail to: @user.email, subject: @subject
   end
+
+  def bitcoin_donation_confirmed
+    @user = params[:user]
+    @donation = params[:donation]
+    @subject = "Donation confirmed"
+    mail to: @user.email, subject: @subject
+  end
 end