Postfix on BSD is bulletproof.
edoceo, the reason your flippant comment is irrelevant and unhelpful is that running an SMTP service means dealing with often intractable deliverability problems that are only surmountable by having your mail sent by a server that sends a large volume of legitimate email to build reputation as a sender.
It doesn't matter if you use postfix, exim, sendmail, BSD, Linux, or TempleOS, or manually wiggle magnets towards an open socket to send email, the reason the GP wants paid SMTP is so that he can rent access to a server with adequate deliverability to actually use his email.
Do you have good deliverabikity to Google and MS hosted mailboxen?
Could had sworn there were a lot more work/tech required, a couple of years ago.
Also did you have to research your IP/domain that your VPS sits behind? Domain blacklists, and avoiding them, seems pretty straightforward. But I've heard mixed things about VPS ips, some mail services could block whole networks from VPS providers while others don't care as long as you don't spam?