I agree with the first part -- always ask people for permission, probably by kicking them a sweetener (e.g. "1 month email course on X"). I have data that I cannot show you which is in you-could-run-your-company-on-just-this-trick violent disagreement with the second point here. If you don't like email, cool, but email is worth serious money in B2B software sales. (So are salespeople, by the way, even at pricepoints lower than you'd think would warrant a salesman. Think "4 figure LTV." + )
Also, at the risk of stating the obvious, every email-deleting-salesmanship-hating engineer in the world could drop dead of a heart attack tomorrow and neither buyers or sellers of enterprise software would notice until several months later when trying to figure out why the sales engineers stopped submitting expense reports.
+ Addendum: Joel Spolsky's famous Camels and Rubber Duckies article talks about there being basically two price points for sales now, but a combination of a better delivery mechanisms - SaaS - and better sales procedures/technologies opens up a bunch of very interesting options in the middle for something between BCC $30 "Every email from a customer is a wonderful opportunity to fix that from happening ever again" and steak-dinners-and-Powerpoint-decks enterprise sales for $75k+.
I have some amount of knowledge about this these days, since I help my clients implement it. If you're interested in hearing more, say so, I'll try to blog it (some day when I get out from a mountain of work and email).