Mailshell is not a well-known name. The firm specializes in spam and phishing control software, for other software vendors. Thus its clients include Oracle, CyberGuard, Panda Software, ZyXEL, Broderbund and Lyris, who have included MailShell’s software into their own offerings and private labelled them.
The firm is small, tightly run, privately held, and appears to have healthy finances. A recent announcement, Message Partners Introduces "Powered by Mailshell" Spam and Phishing Protection, suggests Mailshell is trying to get more public visibility for its brand.