code: func (m *MailYak) Bcc(addrs ...string) {
  	m.bccAddrs = []string{}
  
  	for _, addr := range addrs {
  		trimmed := m.trimRegex.ReplaceAllString(addr, "")
  		if trimmed == "" {
  			continue
  		}
  
  		m.bccAddrs = append(m.bccAddrs, trimmed)
  	}
  }
docs: // Bcc sets a list of blind carbon copy (BCC) addresses.
  //
  // You can pass one or more addresses to this method, none of which are viewable to the recipients.
  //
  //	mail.Bcc("dom@itsallbroken.com", "another@itsallbroken.com")
  //
  // or pass a slice of strings:
  //
  //	bccs := []string{
  //		"one@itsallbroken.com",
  //		"two@itsallbroken.com"
  //	}
  //
  // 	mail.Bcc(bccs...)