Hosted Spamfilter is a spam filter that continuously assesses the likelihood that an incoming email can be categorized as spam, malware, spear phishing or the like. This means that all unwanted mail is sorted out and placed in a quarantine area over which the user has full control.

Over time, Hosted Spamfilter can achieve an average filtering accuracy of over 99.98% and a false-positive error rate (emails that mistakenly reach the recipient) of under 0.0001%. If the system is in doubt as to whether an e-mail should be blocked, it will appear on the user's "Spam Quarantine" list. Here, the user can choose to whitelist the e-mail in question or the sender, so that future e-mails from the same sender are also approved.