No violation has been committed. The mailer didn't cite any law or ordinance or imply such.
UPDATE 5:00am: It looks like Howie might have found the trail, via a professor in Northern Iowa named Christopher Larimer. Describing a previous stunt like this in Alaska. As outlined in a 2014 PBS article:
[…] “Why would they think that shaming would make people comply?”
Because, well, it does. That’s according to Chris Larimer, associate professor of political science at the University of Northern Iowa. And he’s done the research to prove it.
“We found that when you make people aware of the norm of voting and that somebody else is going to observe whether or not you vote, people are more likely then to vote,” he said.
http://theconservativetreehouse.com/2016/01/30/unbelievable-ted-cruz-campaign-sends-out-personal-shaming-letters-to-iowa-voters/ The letter from the so-called Alaska State Voter Project is nearly identical, word for word, to one that Larimer and other researchers tested in Michigan, right down to the typography and punctuation. In that 2006 research, Larimer and colleagues sent voters one of four different letters.
The softest message just urged people to do their civic duty and vote. The most aggressive letter matched the Alaska mailer. It included the addressee’s voting history as well as those of their neighbors, and contained something of a threat by promising a follow-up letter to show the results of the upcoming election.
Larimer says they got complaints, but the technique worked quite well. (read more)
That emboldened segment describes the current Cruz Campaign mailer 100%. Also, Chris Larimer is noted in this recent Texas Tribune article about the controversial debate:
[…] For Cruz, the No. 2 candidate in many polls, Trump’s snub could make him the center of action at the Iowa Events Center, a role that comes with both risks and rewards.
http://theconservativetreehouse.com/2016/01/30/unbelievable-ted-cruz-campaign-sends-out-personal-shaming-letters-to-iowa-voters/
