In my day job I help keep spam out of your mailbox. I work for a company that provides spam filtering services for many major ISPs world wide including most of the US cable companies. We also collaborate with email service providers to help prevent spam and unwanted email being sent in the first place. I just completed a study looking at the email practices of the different presidential election campaigns. Ted Cruz came last for various reasons. One thing the Cruz campaign did that left my boss (who is not a politics junkie, but cares about email) shocked was borrowing spammers techniques of using misleading Subject and From headers to try to trick the recipient into opening the emails. For instance:
This email was only sent to subscribers, so it was not spam in the traditional sense, but if people get used to clicking on fake delivery and expiry notices expecting to get the latest from Ted, they will pretty soon be opening spam and malware, too.
Cruz got the lowest score in my study, though none of the campaigns did very well, apart from Pataki, who was our ideal candidate. He used double opt in to confirm that we really wanted to be on his mailing list, and then suspended his campaign before he could send any more emails! Huckabee was not really trying, he never sent a single email. Carson sent nothing for two months, then turned the email address over to a local volunteer who does not provide an unsubscribe link. I think he’s in the not-really-trying category, too.
Rand Paul was relentlessly garrulous, averaging about two emails a day. My favorite was the one where he compared Donald Trump to Gollum and himself to Aragorn.
You can read the whole study here