When choosing your sales and marketing techniques, dont look at them singularly, but rather in tandem how do they work together and help each other? For example, a mailing by itself might not have much impact. However, when combined with a telemarketing campaign and local seminars, it could get big results.
Bruce Milne wrote this 20+ years ago In his series on Software company Guerilla Marketing. Modifying the message to include email and webinars, its as true today as it was then.