By way of a counter-anecdote: I've been running my own email for 8 years and spend almost no time on it. I can't recall having to do any maintenance at all in the last 3 years.
I do something similar, but when I send an email to a person for the first time, it always ends up in the spam folder by GMail.
Taken from my smtpd.conf:
table secrets { mylogin = [email]@ziggo.nl:[pass] }
accept tagged DKIM for any relay via tls+auth://mylogin@smtp.ziggo.nl:587 auth <secrets>It kind of defeats the purpose, since now the third-party will be able to read all my outgoing emails, and have control over them.
Relaying via the ISP's mail server though (even with TLS) seems like it would disclose the message contents.
By the way, give a look at mail-in-a-box, another cool project that implements a ready to use mail server with great functionalities.