The problem with email nowadays... is that it is an antiquated technology.
There used to be a battle for it in the earlier days of the internet. Just as was the case for search engines. Before "google it" became a coined phrase, there was much competition between search engines of sorts; google, yahoo, lycos, msn, AOL, excite, you name it. Google ended up coming out on top of this battle.
Non-ISP email services experienced much competition before Gmail came out in 2004. Hotmail, Yahoo and AOL were the big three, but Gmail took over by storm very quickly, especially given how well it works with Google as a search engine.
That said, it's been some time before any new players could come to the table in respect to email.
Getting to the point, while it's a very good keyword, I can't picture it being worth much past what you can get from type-in traffic it might get.
Starting an email service is no small investment, and I can't imagine how any new one could make big money. It's just too dicey a business.
I concur with Katherine's valuation. It's
cool domain, but not a
useful domain.
I'd sure like the idea of being able to say, "yeah, send me an email;
[email protected]". That's got awesome factor written all over it. That, I think is the highest and best use for this name.