Laravel6.18.19如何优雅的切换发件账户

<?php
return [
 'emails' =  [
  'a' =  [
   'email' =  'a@188.com',
   'password' =  '专属客户端密码',
   'smtp' =  'smtp.188.com',
   'port' =  '465',
   'encryption' =  'ssl',
   'name' =  '靓仔A',
  ],
  'b' =  [
   'email' =  'b@188.com',
   'password' =  '专属客户端密码',
   'smtp' =  'smtp.188.com',
   'port' =  '994',
   'encryption' =  'ssl',
   'name' =  '靓女b',
  ],
 ],
];

<?php
namespace App\Mail;
use Illuminate\Support\Facades\Mail;
 
class MailHelper
{
 public static function setAccount($accountName)
 {
  $transport = new \Swift_SmtpTransport(
   config("my_emails.emails.{$accountName}.smtp"),
   config("my_emails.emails.{$accountName}.port"),
   config("my_emails.emails.{$accountName}.encryption")
  );
  $transport- setUsername(config("my_emails.emails.{$accountName}.email"));
  $transport- setPassword(config("my_emails.emails.{$accountName}.password"));
  $mailer = new \Swift_Mailer($transport);
  Mail::setSwiftMailer($mailer);
  Mail::alwaysFrom(config("my_emails.emails.{$accountName}.email"), config("my_emails.emails.{$accountName}.name"));
 }
}

<?php
MailHelper::setAccount('a');
Mail::to('boy@163.com')- send(new TestMail());
MailHelper::setAccount('b');
Mail::to('girl@163.com')- send(new TestMail());