Network vulnerability and port scanning services

I've automated scanning before, but did not use an outsourced scanning service. On the topic of outsourced security services for scanning, many people I know swear by Rapid7. They also have HD Moore on staff so they certainly know penetration testing and Metasploit.

It is trivial to use Nmap or Nessus scripted, encrypt the output and send it to yourself via email.

You could also regularly assess compliance with a hardened baseline to ensure they are not deviating from it over time, or introducing new risks..

If you are a security guru, I'd keep it in house, but otherwise, I would outsource it.

Keep in mind that to get accurate results from vulnerability scanning & compliance analysis, you'll need to perform authenticated scans from inside the firewall(s).