Congrats on launching and shipping! Just a note: your landing page is still a little confusing as far as what File Mess can do.
Are you using Context.IO[0]? I just (re-)discovered their platform earlier this week and definitely makes it easy to get started if you're hacking an email processing/automation system (which can be significantly profitable in the B2B space).
Mailgun is another great email API platform. I built and launched imgpage[1] just a few days ago and couldn't have done it without them. Had a few questions, Mailgun support was fantastic.