Mail-shell n. : A chiton.

Example:
how is it authentic actually i received a job openings mail from shell oil company london?

Taxonomy
Mailshell, OEM, reputation, SDK, junk email, phishing, anti-spam program, OEM partners, block spam, consumers, spam programs, anti-spammer, phisher, email fraud, sender authentication, Oracle, Panda Software, CyberGuard.

Defination from the web:
mail samples before subscribing.