Ruby on rails Rails：向多个收件人发送邮件（奇怪的格式）

我想向多个收件人发送邮件，以下是我的资料：

def teaser(customer)
    @customer = customer
    mail(to: customer.shop.email, subject: "Here's an interesting stat")
    mail(to: "admin@mysite.co", subject: "#{customer.shop.email} had an interesting stat")
  end

但是我现在收到的电子邮件admin@mysite.co有非常奇怪的格式。电子邮件内容以不同格式重复3次，首先是：

----==_mimepart_563ad1e4c3af4_9d3f90c47cfe7c324dc Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding

---

我做错了什么？

如果您的客户在阵列中

 def teaser(customers)
        customers.each do |customer|
         mail(to: customer.shop.email, subject: "Here's an interesting stat")
         mail(to: "admin@mysite.co", subject: "#{customer.shop.email} had an interesting stat")
      end      
end

---

当我尝试使用Action Mailer向多个收件人发送多部分电子邮件时，邮件正文中的MIME类型信息也遇到了同样的问题。我最初与客户有一个ActiveRecord关系，然后试图通过他们一次发送一封电子邮件

customers = User.where(access: "customer") 

   customers.each do |customer|
     mail to: customer.email, subject: "email subject test"  
   end  

但是我不得不将一个数组或逗号分隔的列表传递给邮件发送程序，从而解决了邮件正文中MIME类型信息的问题

  customers = User.where(access: "customer") 
  customers_emails = customers.map {|c| c.email}  
  mail(to: customers_emails, subject: 'testing')

---

不是我想解决的问题。我的问题是，我的代码发送的电子邮件格式非常奇怪，正文中包含MIME类型