The problem with starting an e-mail service is the crazy level of administration and sysadmin headaches it induces merely to be able to reliably send e-mail to 90%+ of endpoints.. let alone anything else.
The engineering problem is a pretty interesting one, but the headache of ensuring your users can actually get their mail someplace makes it seem dull or insurmountable to solo developers.
Yeah, I second this. Handling people's email is not fun at all, and 90% is way too low IMO. 90% would mean that 1 in 10 of someone's emails wouldn't make it to where it was supposed to.
Users start to get annoyed if you do any worse than 99.9%, and they don't like receiving any spam at all, and to make matters worse, "the other end" can be anything from a creaky old sendmail server to an Exchange monstrosity, either of which can communicate in odd ways or drop a message altogether.
I keep expecting to see email go the way of Usenet, but it keeps refusing to die.
I completely agree. Not only that, but users will typically deal with lots of software annoyances, but one thing they simply will not tolerate is late or lost email.
Having spent far too much time figuring out problems in a fairly large email system (120 servers, world-wide, just about every MTA known, including Notes) I can heartily agree - there are just so many obscure ways that email can fail that it's really not funny.
