I just looked they have a service called “alternative port 25” that addresses this issue.
Honestly though, once you start adding up costs for these workarounds you have to wonder if it’s easier to just get a business internet circuit, cloud security gateway, or just host the email online.
If I wanted to do this today I would use iTunes and an old iPhone as the mp3 player. I would use an old laptop to rip, or iTunes to purchase.