E-mailing Cravaack? Have a Phone Number Ready

Rep. Chip Cravaack (R-MN(?)/NH) has taken a good deal of criticism, all of it deserved, for avoiding his district (MN-08) and its residents.  His campaign has tried to respond, including by offering fulsome "thanks" to Cravaack on an annoying billboard "For Listening and Reaching Out."

It so happens that I'm an inveterate signer of online petitions.  I know that they're unlikely to change the world, and to be honest the main reason that I e-sign them is to make sure that I keep getting mailings from those organizations, as they're often replete with useful information.  Plus, I figure that another name on them, can't hurt.  I would estimate that at least two out of three times that one is directed to Cravaack, I get something like this:

In other words, the e-mail won't go through, unless I provide a phone number, presumably so his staff can call and interrupt my activities and reflections, to hassle me for money or whatever.  "...Listening and Reaching Out," all right.

I don't know whether this is common practice, for members of either or both parties.  I do know that it frankly strikes me as classless and cowardly.  I also know that I've never seen anything like it, while directing petitions to Sen. Amy Klobuchar (D-MN) or Sen. Al Franken (D-MN).  Or, for that matter, to my (conservative) state legislators, Rep. Sondra Erickson (R-Princeton) and Sen. Dave Brown (R-Becker).  And I have to wonder if it's indicative of a campaign that is more than a little desperate.