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What is an email blocklist?

A DNS real-time blocklist (blacklist) contains a list of unsafe items seen in DNS traffic. Blocklists are used in network security architecture in real-time to mitigate abuse of APIs, DNS, communications, email, and identity. Directory servers, DNS servers, firewalls, gateways, messaging servers, and web proxies are examples of systems that use blocklists.

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Who should use a DNSRBL email blocklist?

Our plug-and-play DNS email blocklists benefit anyone who operates an on-premise mail server or uses a single-tenant 3rd party cloud email service. Using a well-designed DNS email blocklist suite, email servers can quickly reject unsafe messages when unsafe DNS resources are identified. This saves processing overhead, maximizes user mailbox safety, and helps identify compromised users and bad actors on the platform.

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How can Guardian Mail benefit me if I already have an existing email security solution?

Guardian Mail catches over 99.6% of malicious traffic during the initial inbound connection, usually in less than a second. As the first line of defense for your mail servers, it protects your users from spam, scams, phishing, and malware. In addition, Guardian Mail:
  • Saves CPU overhead, leading to significant scaling gains
  • Reduces hardware requirements
  • Integrates with most email servers, spam filters, and security solutions.

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I’m using Google Workspace or Microsoft 365. Can I use a DNS email blocklist?

If you run an email gateway in front of Google Workspace or Microsoft 365 and have your domain’s MX records pointing to these gateways, you can use blocklists upstream of Google or Microsoft.

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Should I use more than one blocklist?

Having accurate, reliable, and well-supported email filtering is crucial for its effectiveness. If you are considering switching vendors but are still unsure, take a look at our Comparison Tool Overview to let you compare our effectiveness.

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Are DNSRBL email blocklists used on inbound email?

Using a DNS email blocklist suite with your inbound mail server can block bot traffic, spam, phishing, and malware from reaching your users. More than 99.6% of malicious traffic can be bounced before it reaches your content filtering stage. Real-time lists within the suite can also help your content filters recognize other content, such as domains used in URLs and short and disk storage URLs that change regularly. By bouncing spam, phishing, and malware that has already been identified in DNS early in the message receipt lifecycle, you can reduce your mail server resource overhead, storage, and user risk. Furthermore, by removing general messaging noise, you can focus your content filtering efforts on identifying more precisely targeted malicious message content aimed at your organization and its users. Guardian Mail blocks inbound mail during the (a) TCP/IP connection, (b) SMTP session, and (c) content evaluation cycle. By using Guardian Mail, mailbox providers can dramatically reduce user security risks and messaging overhead.

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Are DNSRBL email blocklists used on outbound email?

Using a DNS email blocklist suite with your outbound mail server can help you identify users with compromised systems early on during the authentication stage of sending emails. Real-time DNS lists can also help your outbound email server recognize domains, short URLs, and disk storage resources associated with compromised accounts and bad actors, reducing the likelihood that your mail server will become blocklisted. By identifying users associated with compromised systems and accounts, you can issue an immediate password reset to the user and warn them of the hazard on their machine, thereby preventing bots from using the user’s password and sending malicious emails. If the user is a bad actor, they will tire from resets and move on to other resources. Additionally, you can reduce the likelihood that your server will be blocklisted for these users. Guardian Mail blocks outbound mail during the authentication session and content evaluation cycle. By using Guardian Mail, mailbox providers can dramatically reduce compromised accounts and blocklistings.

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What lists does the Guardian Mail blocklist suite contain?

The Guardian Mail DNS blocklist suite consists of twelve Production and four Beta Zones (or lists). Each list is optimized for specific use in inbound or outbound email and during a different stage of the messaging lifecycle (connection, authentication, SMTP dialog, and content evaluation). see Production Zones and Beta Zones

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What standards does Guardian Mail follow?

Abusix follows the IETF standard RFC-5782 “DNS Blacklists and Whitelists” and M3AAWG “Best Current Practices For Building and Operating a Spamtrap”.

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Can I try Guardian Mail?

Of course! – Just sign up on https://app.abusix.com/signup and start using the service, up to 5000 queries per day are free.

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Can we have a local mirror of the Guardian Mail blocklist suite via RSYNC?

Yes, we only provide RSYNC at an additional fee to large mailbox providers. If you are interested in using RSYNC, please get in touch with us during your trial at [email protected]