What are some alternatives?
Barracuda Email Security Gateway - Barracuda's Email Security Gateway is a powerful antivirus filter specifically designed to identify and eliminate email-borne threats, stopping hazards before they reach the network.
FullContact for Gmail - Your Gmail Contacts. On steroids.
Symantec Email Security.cloud - Symantec Email Security.cloud provides always-on, inbound and outbound email security against malware, targeted attacks, and advanced threats
FullContact for iOS - Better contact management for your iPhone and iPad
Proofpoint Email Security and Protection - Learn about Proofpoint's email security solutions that protect organizations against threats such as email fraud, phishing, spam, bulk email, and viruses.
ContactRescue - Magically get your address book up-to-date and accurate