Summary
While SORBS was historically a significant and long-standing DNS-based blocklist, it has been largely deprecated and deactivated since November 2023. This change means it is no longer actively updated or widely relied upon by Internet Service Providers (ISPs) for email blocking, thus making it generally unimportant for current email deliverability. In its active period, SORBS's impact varied; it often caused deliverability issues for B2B clients and those using smaller or regional mail servers, but had minimal impact on major B2C providers, such as Gmail, Hotmail, or Yahoo, which primarily relied on their own proprietary filtering systems. Proofpoint, which owned SORBS, also used its own independent reputation services despite some data sharing.
Key findings
- Largely Deprecated: SORBS has been largely deprecated and deactivated since November 2023, following its parent company's acquisition, rendering it generally unimportant for current email deliverability.
- Limited Current Usage: It is no longer actively updated or widely used by most major Internet Service Providers (ISPs) for email blocking, meaning it has minimal impact on deliverability today.
- Historical Relevance: Prior to its deactivation, SORBS was a long-standing DNSBL whose impact varied. It historically caused a small increase in bounces for B2B clients and was consulted by smaller and medium-sized mail servers more than major B2C providers like Gmail, Hotmail, or Yahoo.
- Proofpoint Connection: Proofpoint previously owned SORBS and integrated some of its data or shared spam trap feeds, but Proofpoint's own reputation service for their appliances operated independently with different listing criteria.
Key considerations
- Focus on Active Lists: Senders should prioritize monitoring currently active and widely adopted blocklists, as SORBS is no longer a primary concern for deliverability. Resources should be directed towards lists that are actively used by major ISPs and email providers.
- Overall Reputation Remains Key: Maintaining a strong overall sender reputation with major ISPs and email providers through best practices, low spam rates, and positive engagement is paramount, as many primarily rely on proprietary filtering technologies rather than external blocklists like SORBS.
- Diverse Filtering Approaches: Email administrators often use a combination of filtering technologies; understanding the specific requirements and integrated blocklist usage of target recipients' mail servers remains crucial for effective delivery.
- Past Delisting Ease: Historically, when SORBS was active, delisting was often a low-effort process for common issues like trap hits, even for shared IPs, although some users occasionally reported it could be tedious.
What email marketers say
12 marketer opinions
Following its deprecation in November 2023, SORBS is no longer actively updated or a primary concern for most senders. However, before this change, and for specific environments that may still rely on older data or configurations, SORBS was indeed considered an important blocklist with varied impacts on email deliverability. Its relevance stemmed from its integration into several business systems, including some Proofpoint configurations and filtering solutions like SpamExperts, which compile data from multiple DNSBLs. While major B2C providers like Gmail had minimal reliance on it, SORBS frequently affected deliverability for B2B clients and those sending to smaller, regional, or legacy mail servers that continued to leverage its data. Experts noted that even if not a top-tier blocklist, a SORBS listing could contribute to a sender's overall reputation and cause deliverability issues for a significant segment of recipients.
Key opinions
- Historical Importance for Specific Segments: Historically, SORBS held significance for B2B clients and smaller, regional, or legacy mail servers, which often integrated its data into their filtering systems, leading to deliverability challenges for these audiences.
- Integration with Business Solutions: Filtering solutions used by businesses and hosting providers, such as SpamExperts, often combined SORBS data with other DNSBLs, making a SORBS listing a factor for deliverability through these comprehensive systems.
- Varying Impact on Deliverability: Its impact varied; while major B2C providers typically had minimal reliance on SORBS, it could still contribute to a sender's overall reputation and lead to bounced emails for recipients whose mail servers consulted it.
- Proofpoint Ownership Nuance: Although owned by Proofpoint and sharing some spam trap feeds, Proofpoint's primary reputation service operated independently with distinct listing criteria, indicating a nuanced relationship.
- Delisting Process: Historically, delisting from SORBS was generally a low-effort process for common issues like trap hits, even for shared IPs, although some users occasionally found it tedious.
Key considerations
- Current Status is Deprecated: It's crucial to understand that SORBS has been deprecated since November 2023, significantly reducing its current impact on mainstream email deliverability.
- Legacy System Relevance: While largely inactive, some older or less frequently updated systems, particularly in B2B or regional contexts, might still hold cached SORBS data or be configured to consult it, potentially causing isolated deliverability issues.
- Focus on Active Blocklists: Senders should prioritize monitoring and managing their reputation on currently active and widely used blocklists, rather than expending significant effort on a deprecated list like SORBS.
- Holistic Deliverability Strategy: A robust deliverability strategy involves maintaining a positive sender reputation across the board, understanding the diverse filtering methods used by recipient mail servers, and adhering to general best practices, irrespective of specific blocklist statuses.
Marketer view
Email marketer from Email Geeks explains that SORBS can be relied upon by some business systems (like Proofpoint) and might cause a small increase in bounces for B2B clients, but generally has minimal impact on B2C providers such as Gmail, Hotmail, or Yahoo. She notes that delisting is a low-effort process, even for shared IPs, and that listings she's encountered were typically due to trap hits, not open relays.
9 Feb 2023 - Email Geeks
Marketer view
Email marketer from Email Geeks states that SORBS is used by Proofpoint.
12 Jul 2024 - Email Geeks
What the experts say
2 expert opinions
SORBS is currently not an important email blocklist for deliverability. Its significance has diminished due to its effective deactivation in November 2023, a consequence of its parent company's acquisition. As a result, SORBS is no longer actively updated or widely utilized by Internet Service Providers (ISPs) for email blocking purposes.
Key opinions
- Deactivated Since Nov 2023: SORBS has been essentially deactivated since November 2023, following its parent company's acquisition.
- No Active Updates: The blocklist is no longer actively updated or maintained.
- Not Used by ISPs: Most major Internet Service Providers (ISPs) no longer utilize SORBS for email blocking purposes.
- Irrelevant for Deliverability: Due to its inactive status and lack of widespread ISP adoption, SORBS is not an important blocklist for current email deliverability.
Key considerations
- Focus on Current Blocklists: Email senders should concentrate on monitoring and managing their reputation on blocklists that are actively maintained and widely used by Internet Service Providers (ISPs).
- SORBS No Longer a Concern: Given its deactivation, resources should not be allocated to checking or delisting from SORBS for current deliverability efforts.
- Maintain Core Practices: Prioritizing overall sender reputation, list hygiene, and engagement remains paramount for email deliverability, independent of deprecated blocklists.
Expert view
Expert from Spam Resource explains that SORBS has been essentially deactivated since November 2023, following its parent company's acquisition. This renders SORBS no longer important for email deliverability as it is not actively updated or used by Internet Service Providers (ISPs) for blocking.
3 Jul 2024 - Spam Resource
Expert view
Expert from Word to the Wise states that SORBS is largely deprecated and is no longer used by most major Internet Service Providers (ISPs) for email blocking. Therefore, it is not an important email blocklist for deliverability today.
12 Jul 2024 - Word to the Wise
What the documentation says
6 technical articles
While previous discussions confirmed SORBS is largely deprecated and no longer a primary concern for current email deliverability, the documentation sheds light on its historical role and functionality. SORBS was designed as a DNS-based Blackhole List (DNSBL) aimed at assisting email administrators in filtering unsolicited messages and combating spam. Prior to its deprecation, being listed on SORBS could directly impact deliverability for mail servers that integrated it into their filtering rules. Its importance varied; while major providers like Microsoft and Google prioritized their own sophisticated filtering and reputation systems, a SORBS listing could indirectly contribute to a sender's overall reputation. Conversely, many smaller, regional, or specific business mail servers, often configured to query multiple DNSBLs, frequently relied on SORBS, making its listing a direct barrier to email delivery for those audiences.
Key findings
- Historical Purpose: SORBS historically functioned as a DNS-based Blackhole List (DNSBL) to combat spam, collecting data to aid administrators in filtering unwanted emails.
- Varied Adoption: Its impact on deliverability was not uniform; while major email providers largely relied on proprietary filtering, many mail server administrators did configure their systems to query SORBS, leading to direct rejections.
- Multi-DNSBL Strategy: For servers utilizing a multi-layered defense, SORBS was often part of a suite of DNSBLs queried, signifying its role in broader spam prevention efforts.
- Indirect Reputation Influence: Even where not directly blocking emails, a SORBS listing could negatively affect a sender's overall reputation, impacting how their emails were perceived by more comprehensive filtering systems.
Key considerations
- Focus on Active Blocklists: Given SORBS's current deprecation, senders should prioritize monitoring and managing their reputation on actively maintained and widely adopted blocklists.
- Understand Diverse Filtering: It remains crucial for senders to understand that mail servers utilize diverse filtering technologies and may consult various blocklists, necessitating a broad approach to deliverability.
- Holistic Sender Reputation: Maintaining a strong overall sender reputation through best practices, low spam rates, and positive engagement is paramount, as major providers primarily base deliverability on these factors.
- Impact of Any Significant Listing: While SORBS is no longer active, the principle that any significant blocklist listing can negatively contribute to a sender's reputation and lead to deliverability issues still holds true for currently active lists.
Technical article
Documentation from SORBS DNSBL - The SORBS Zone explains that SORBS is a DNS-based Blackhole List that collects data on spam and attacks, providing various zones to help email administrators filter unsolicited email. Its purpose is to assist in identifying and blocking potential sources of spam, which inherently impacts deliverability for senders listed.
25 Oct 2021 - SORBS DNSBL - The SORBS Zone
Technical article
Documentation from Spamhaus, a leading anti-spam organization, implicitly suggests that while many DNSBLs exist, the most significant impact on deliverability typically comes from those widely adopted by major ISPs and email providers. While SORBS is acknowledged as a long-standing list, the degree of its importance varies depending on the specific filtering rules and reliance of target recipients' mail servers.
31 May 2022 - Spamhaus
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