Is this still a good way of marketing?

[Cute]

Is mail still a good way of marketing?
I want to offer mobile marketing to cosmetologist who want to get back customers and keep existing clients coming back. for instance woman will put off going back for there color treatment and perms sometimes but will Mobile marketing reminding customers or offering them coupons might keep them coming more often and I do not see a lot of cosmetologist advertising on facebook or twitter so if I send a post card size ad in the mail offering a free information seminar on mobile marketing do you think it would work. I would be offering it at a very cheap price.