Outlook Spam Filter

Spam filters recognize spam mails based on typical content such as frequently used links or the tracking pixels that spammers like to use. The known mail servers that are used for sending spam are added to so-called grey lists by email providers and intercepted directly by the mail server. This way, they don’t reach your PC and don’t need to be checked by the Outlook spam filter. Greylisting is the most resource-saving method against spam and is based on so-called Domain Name System-based Blackhole Lists (DNSBL) – real-time retrievable blacklists for dubious email addresses.

Furthermore, it is important that a junk filter in Outlook is trained by a user to improve its detection rate. When you receive a spam mail in your inbox, it’s best to mark it as spam rather than simply delete the message. This ensures that the spam filter learns which emails are spam and increases its hit rate. The same applies to emails that have been identified as spam by mistake. Mark them as “Not Spam” so that the system no longer filters similar emails in the future. You can also set the spam filter to block certain email addresses as a matter of principle.

Check your spam folder regularly and adjust the spam filter rules if emails are detected incorrectly. How this works depends on the Outlook version you use. In the following, we will show you how to optimally configure your Outlook junk filter.

Microsoft Outlook is a popular email client, but many businesses have reported receiving excessive volumes of spam in their inboxes which has led them to search for the best spam filter for Outlook. Fortunately, improving spam filtering for Outlook is relatively straightforward.

Outlook is commonly used with Microsoft Office 365, although other mail services can also be connected to Outlook. As with any email service, users of Outlook must deal with spam email, phishing and other email threats. Microsoft does provide a basic spam filtering service through Exchange Online Protection (EOP), but it is not sufficient to protect against advanced email threats.

A more advanced level of protection is available to Office 365 Enterprise E5 customers in the form of Advanced Threat Protection (APT). APT can also be added to other subscription plans for Outlook to improve protection against advanced threats such as spear phishing and zero-day malware.

If you want to improve the spam filter for Outlook, you will no doubt want to evaluate Microsoft’s solution and third-party Outlook spam filters. To help you whittle down the list of anti-spam service providers and find the best spam filter for Outlook, we have listed some of the most important features of spam filters for Outlook.

If an Outlook spam filter has these features, it will help you to block more spam and email threats and better protect your email system and network.

Microsoft’s basic level of protection, EOP, does offer a reasonable level of protection against spam and unsophisticated phishing attacks. Users find the majority of spam and malicious messages are blocked and do not reach inboxes. However, a significant percentage of phishing emails bypass EOP controls and are delivered to end users.

One of the problems is Office 365 users are targeted by cybercriminals. A company using Office 365 has this broadcast through its MX record so cybercriminals can identify Office 365 users and target their campaigns accordingly. Cybercriminals can test their own Office 365 accounts to see if their carefully crafted messages bypass EOP defenses and arrive in inboxes. According to a study conducted by Avanan, around 25% of phishing emails reach EOP-protected Outlook inboxes.

The advanced anti-spam service for Outlook provides a much greater level of protection than EOP. Business users therefore need to pay for APT or use a third-party anti-spam service if they want to reduce the threat from phishing and malware to a reasonable and acceptable level, but which is the best spam filter for Outlook? APT or a third-party solution?

The best spam filters for Outlook incorporate extensive front-end checks for all incoming emails to determine the likelihood of a message being spam or malicious. The most advanced third-party spam filters for Outlook incorporate the features listed below. These ensure virtually all spam is identified and prevented from reaching inboxes, while advanced anti-malware features ensure that emails containing infected attachments or malicious code are quarantined or deleted.

The following features are not present in EOP but are included in many third-party spam filters for Outlook to ensure greater protection of the email system.

Features

• Dedicated Real-Time Blacklists (RBLs): RBLs are lists of IP addresses known to be used for spamming and malware distribution. The use of multiple RBLs ensures spammers are identified faster.
• Greylisting:The process of rejecting messages and requesting they be resent. The time delay is an indicator of whether the originating server is being used for spamming.
• Data Loss Protection: Data loss protection measures can be implemented to create custom policies that delete, redirect, or bounce emails that breach certain user-set rules.
• Multiple Antivirus Engines: Multiple anti-virus engines and threat intelligence are combined to improve malware detection rates. If one AV engine fails, a secondary engine will ensure malware is still blocked.
• Advanced Malware Protection: Predictive techniques, Bayesian analysis, heuristics, and machine learning are used to improve detection rates for zero-day malware. Sandboxing may also be included. This allows deep analysis of suspicious attachments for malicious actions.
• URL Scanning: The scanning of all embedded hyperlinks in real-time against blacklists to identify URLs used for malware distribution, phishing, and other online scams.
• Customizable policies:The ability to set custom policies for individual users and departments. Spam thresholds can be set for different mailboxes. Departments that are targeted by phishers (HR, accounts, C-Suite) can have more aggressive controls set.
• DMARC authentication–Authentication of emails to make sure the sender of an email is authorized to use that domain. This is an important measure to protect against email impersonation and BEC attacks.