Sending is actually 1/3 of email. The other two are receiving and storing. :)
Even sending by itself is such a complicated beast that only a select few allow customers to do it properly, and to properly do sending you must have receiving end set up as well. Your deliverability goes up when you allow replies to the sending host. ESPs see replies as participation and it makes a difference. That's why we keep preaching: No more no-reply emails.
Another elephant in the room is spam. If you silently accept everything coming to your MX host, you're asking for it. That's how some email platforms do the receiving end. GMail can get away with this because they employ a small army of PhD's to deal with spam. To have manageable volumes of spam, you've got to be able to generate SMTP bounces for invalid addresses. The list of things to do in order to receive properly goes on and on. Hooking up incoming SMTP traffic to a Python function is the easiest part of receiving mails.
Long story short: if email is critical to your app, you have very limited options. Roll your own or sign up for Mailgun, which is basically a Gmail-like back-end which makes your application look and feel like a real email server to other ESPs, not a mass sender of $0.0001 emails. Mailgun also has other advantages like automatic cleanup of garbage MIME bodies - this always hits you hard in production, and standard MIME parsers for most languages won't cut it.
I really wish Mailgun.net was a nicer website. It's terrible of me, but I just can't take Mailgun seriously with such an.... amateur website, I just can't accept that it's a legitimate company. Postmark on the other hand (and mailchimp etc.) have really nice websites, it makes me want to use them.
Agreed 100%. We've been slacking on the web design fronts. Check out the design of our APIs instead! :) We invested all our attention to the queue, to maintaining high traffic quality and the parsing engines.
Check back soon and I'm sure you'll be pleasantly surprised!
Al from EmailYak here - I'm happy that people are finding the service useful as it looks now, but we're also going to overhaul our design and explain the service better. Here's a sneak preview:
