You can use a heap of patches for qmail, but I wouldn't recommend it. I was using Courier MTA for a while for self-hosting email. I may do so again, and will

You can use a heap of patches for qmail, but I wouldn't recommend it. I was using Courier MTA for a while for self-hosting email. I may do so again, and will likely use mailcow or mail in a box. Neither are based on qmail.