Mail Sentinel® Anti-Spam offers customizable spam blocking for GTA's firewall email proxy. Simply utilize the email proxy on your GTA firewall for your SMTP email, and activate the Mail Sentinel Anti-Spam subscription – no software to download and install.

Mail Sentinel Anti-Spams greylisting settings offer enhanced email filtering before the email reaches the email server. Greylisting is designed to protect users from spammers that use fire and forget email applications, which are created to send spam messages, but never attempt to retry delivery if the first attempt fails. Greylisting significantly reduces the number of emails which are scanned by spam rules, so email processing is more efficient. With a two pronged attack on email, spam is virtually eliminated while legitimate email is efficiently processed and received at the users inbox. Mail Sentinel Anti-Spam is powered by MailShell Anti-Spams Spam Recognition System. Each message is reviewed by four separate spam identification engines that utilize over 300,000 rules to identify unsolicited email. Mailshells four spam identification engines check for a variety of characteristics that exhibit spam-like behavior, such as spam attacks, phishing techniques, image spam, and others. This unique spam identification system provides a high accuracy rate, all while preventing false positives.

Mail Sentinel Anti-Spam is powered by MailShell's Anti-Spam technology. This technology reviews each message in fractions of seconds by four spam identification engines utilizing more than 300,000 algorithms and rules to identify spam with a high accuracy rate while preventing false positives. “Phishing” and other fraud-based definitions are established based on SpamRepute Index, an advanced statistical analysis-based method of quantifying email senders' reputations and is included in the SpamCompiler technology. The results are combined using SpamScore, a proprietary Bayesian statistical formula, into one final spam probability score. The Mail Sentinel Anti-Spam subscription option automatically check for rules updates to ensure the accurate weighting against the most up-to-date rules for formulation of the spam probability score.

SpamScore rankings range from 0-100 and are utilized by Mail Sentinel Anti-Spam subscription to rank emails as spam (confirmed) or probable (suspect). Firewall administrators can establish thresholds based on SpamScore for confirmed and probable spam to fine tune the control of the spam filtering to match corporate needs. Once Mail Sentinel Anti-Spam thresholds have been established, administrators may choose to accept, reject, tag or quarantine confirmed or suspected spam emails. Each email is then assigned a SpamScore, which can be viewed in the email header, and then handled according to the category and rules assigned by Mail Sentinel Anti-Spam.

When used in conjunction with Mail Sentinel email proxy ACLs, white lists and black lists a corporation can virtually eliminate spam emails delivered via the firewall email proxy.