Ruby on Rails

Random issue with my ruby on rails application out of the blue. I'm getting a 501 error each time a user tries to submit the form. This error does not occur when I'm running the app locally, it only occurs when I push to Heroku.   

> heroku logs --tail(The error shows up below)

Net::SMTPSyntaxError (501 Sender syntax err$│

                  app/controllers/contact_controller.rb:38:$

    def tour_create

    @message = Message.new(params[:message])

    @message.type = "Tour"

    @message.save

    if @message.valid?

              UserMailer.tour_signup(@message).deliver

              flash[:notice] = "Thank you for your interest in  You'll receive an email from us confirming your participation in this Thursday's tour within 24- 48 hours."

              redirect_to("/tour/confirmed")

          else

            flash.now.alert = "Please fill all fields."

            render :tour_new

              end

      end

>usermailer.rb

    class UserMailer < ActionMailer::Base

      default from: "string"

    

    

      def tour_signup(message)

      @message = message

    

    mail(:to => message.email, 

    :cc => "string that is an email goes here", 

    :subject => message.first_name + ", Let's Tour This Wednesday"

    )

      end

    

      def orientation_signup(message, date)

        @message = message

        @date = date

    

        mail(:to => message.email, 

          :cc => "email", 

          :subject => message.first_name + ",string that gets sent to users inbox

        )

      end

    

      def ask_a_question(message)

      @message = message

    

    mail(:to => "emailstringgoes here", 

    :subject => message.first_name + " Has A Question"

    )

      end

    

      def trial_kickoff_confirmation_to_user(message, type)

      @message = message

      @date = message.event_time.strftime("%l:%M %P, on %A, %B %-d")

        @type = type

        type_subject = type.split.map(&:capitalize).join(' ')

    

    mail(:to => message.email,

    :subject => "Your #{type_subject} Has Been Scheduled!"

    )

      end

    

      def trial_kickoff_confirmation_to_hosts(message, type)

      @message = message

        @date = message.event_time.strftime("%l:%M %P, on %A, %B %-d")

        @type = type

        type_subject = type.split.map(&:capitalize).join(' ')

    

        if type == 'kick-off day'

          email = 'email'

        else

          email = 'email'

        end

    

    mail(:to => email, 

    :subject => "#{type_subject} for " + message.first_name + " " + message.last_name

    )  

      end

    

      def new_member_from_batchbook(member, password)

        @member = member

        @password = password

    

        mail(:to => @email, 

          #:cc => "emailgoes here string", 

          :subject => "#{@first_name}, finish your profile at string.com!"

        )

      end

    

    

      def member_import_notification message, status

        @message = message

        @status = status

        mail(

          :to => 'em...@string.com', 

          #:cc => "em...@string.com", 

          :subject => "#{@message['first_name']}, import to em...@string.com #{status}!"

        )

      end

    

      def no_new_member_notification

        mail(

          :to => 'em...@string.com', 

          #:cc => "em...@string.com", 

          :subject => "Import ran. No new members!"

        )

      end

    end

> .ruby-env

    bash -c 'echo "POSTMARK_API_TOKEN=`heroku config:get POSTMARK_API_TOKEN`" >> .env'

    bash -c 'echo "POSTMARK_SMTP_SERVER=`heroku config:get POSTMARK_SMTP_SERVER`" >> .env'

    bash -c 'echo "POSTMARK_INBOUND_ADDRESS=`heroku config:get POSTMARK_INBOUND_ADDRESS`" >> .env'

> Procfile

> web: bundle exec rails server -p 3000