There was another service that did this and did it well. But apparently it isn't around anymore. It was called Mail Finch. Here is the Mixergy interview, IMHO it's great: http://mixergy.com/mailfinch-paul-singh-interview/
The first I heard of a service like this was
letters.com back in 1994. My friend started it.
He ended up selling the domain for 5 figures
and went on to do the webcounter at digits.com.
AOL used TeleMail/SprintMail for this around 1992; Sprint provided an X.400 gateway to both fax and US postal mail, but IIRC the postal mail gateway cost something like $1/page and so nobody ever used it:
