Yes I know I am using it. I just think API, built-in API should be standard. Creating separate mailbox for each self hosted service I am running and testing it and making sure it is using TLS instead of STARTTLS or other way around and fixing user name because some services send using domain and some not, and setting correct port because 465 did not work even if it should be using SSL... It is so much hussle. Maybe it was fun when I was doing PHP forms 20 years ago but not now. Now I want to have just API with /mail/send and API key and forget about all of that.