Is voxer.com Safe?

Although I never contacted voxer.com, they sent me email every day for a week. So, either they bought a list of email addresses and began spamming me, or someone registered my address in error. Voxer does not depend on opt-in confirmation, AKA double opt-in, resulting in spam. I believe that any commercial entity that spams is inherently untrustworthy. Their first email said "Complete your registration. Verify your email address." However, unlike the ethical sites which invalidate any registration attempt that isn't verified, Voxer treated this invalid registration attempt as valid. For example, they sent me connections to two people, giving me their first and last names--people whom they said they had already allowed to contact my unverified, anonymous, phony account, thus encouraging a potentially unsafe connection.