Both conservative and liberal campaigns have used similar mailings since 2004 in many states. I posted two articles about it earlier.
http://www.freerepublic.com/focus/f-news/3390772/posts
http://www.freerepublic.com/focus/f-news/3390778/posts
A mistake is still a mistake, no matter how many make it. I’ve worked in and managed campaigns for years, and I can say with confidence that this sort of thing is often a campaign killer. It should NEVER be done in a campaign appealing to people who look for honesty as a priority in a candidate; as Evangelicals do. Even when tried by those with fewer scruples who are losing and desperate, it very rarely works.
Ted Cruz should not have been desperate. Nobody “wins” Iowa. Delegates are chose proportionately and both Trump and Cruz would have wound up close to a tie. All the Primaries are proportionate until March.
Most important, by taking ownership of this mailer, his greatest asset has been compromised; his character.