How do I deal with a SORBS listing affecting email deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 19 Jul 2025
Updated 16 Aug 2025
8 min read
Discovering that your IP address or domain is listed on a blocklist like SORBS can be concerning, especially when you're focused on ensuring your emails reach their intended recipients. When I first encountered a client with a SORBS listing, my immediate thought was, "How significant is this, and what's the fastest way to get off?" However, what I've learned through experience is that the impact of a SORBS listing on email deliverability, particularly to major mailbox providers, is often misunderstood and overstated.
My goal here is to guide you through understanding SORBS, assessing its actual impact, and focusing on the most effective strategies to maintain and improve your email deliverability, whether or not a SORBS listing is a direct cause of your issues. We will also explore the process of handling a SORBS listing while emphasizing that broader deliverability health is often the true priority.
The Spam and Open Relay Blocking System (SORBS) is an anti-spam DNS blocklist (DNSBL) that lists IP addresses of servers identified as sources of spam, open relay servers, or compromised hosts. While it has been around for a long time, its influence on modern email deliverability has diminished significantly compared to other blocklists (or blacklists) such as Spamhaus or Barracuda. Many major mailbox providers, like Yahoo and Gmail, do not heavily rely on SORBS for their filtering decisions.
In my experience, if your emails are primarily targeting major consumer-facing providers, a SORBS listing might have little to no discernible impact on your overall deliverability. It's a different story if you're sending to smaller, independent mail servers or B2B clients that might be using older or less sophisticated spam filtering technologies that still reference SORBS. These environments could still block your mail based on such a listing. For a deeper dive into SORBS's current relevance, you can read more about whether SORBS is an important blocklist.
The key takeaway is not to panic. A SORBS listing is often a symptom, not the core problem. The underlying cause of the listing (e.g., sending to invalid addresses, unsolicited mail, or a compromised server) is usually the true issue affecting your sender reputation and deliverability across the board.
Diagnosing actual deliverability issues
Before you rush to delist, it's crucial to confirm if the SORBS listing is genuinely affecting your email delivery. Many email service providers (ESPs) report a deliverability rate based on whether mail is accepted by the recipient's mail server, not whether it lands in the inbox. This distinction is vital because a 98% acceptance rate doesn't guarantee inbox placement, as mail can still be shunted to the spam folder. To accurately diagnose issues, you need to look beyond surface-level metrics.
The most definitive way to understand if a blocklist is affecting your emails is to examine the bounce messages you receive. When an email is rejected due to a blocklist, the bounce message will explicitly state the reason, often referencing the specific blocklist. Without these direct rejection messages, a blocklist listing, especially on SORBS, might not be your primary concern. This investigation often means digging into your ESP's log files or working directly with their support team to retrieve detailed bounce reasons. Knowing why your emails are bouncing is the first step toward effective troubleshooting.
If you are consistently seeing emails land in spam folders, that indicates a deliverability problem, even if they aren't technically bouncing. In such cases, the issue is more likely related to your sending behavior, recipient engagement, or content quality rather than a specific, less influential blocklist. Focus on the core behavior that led to the listing.
Always prioritize fixing genuine problems that affect a significant portion of your audience over minor flags. I always advise my clients to look at their spam placement rates across major providers like Outlook and Gmail to get a clear picture.
Delisting from SORBS and managing expectations
If, after careful analysis, you determine that the SORBS listing is indeed impacting your deliverability to specific recipients, you can initiate a delisting request. The process is generally straightforward and involves visiting the SORBS website and following their instructions. You'll typically need to enter the IP address in question and verify that the issue leading to the listing has been resolved. While the process itself is not overly complex, SORBS has a reputation for being slow to respond and sometimes difficult to deal with.
Some blocklists, including certain categories within SORBS, may require a fee for expedited delisting. I advise against paying these fees unless absolutely necessary and only after exhausting all other options and verifying the listing is truly causing significant, measurable harm. Often, the effort and cost associated with delisting from SORBS are disproportionate to its actual impact on modern email deliverability. For more detailed guidance, explore how to handle a SORBS listing without paying.
The critical point is to address the root cause that led to the listing in the first place. Delisting without fixing the underlying problem is like patching a leaky roof without addressing the hole, the problem will recur. The same behavior that got you listed on SORBS may also be impacting your deliverability at other, more influential providers, even if they don't explicitly reject your mail due to SORBS.
Focus on delisting
Approach: Primary goal is to remove the IP/domain from the SORBS blocklist.
Action: Submit delisting requests to SORBS, potentially paying for expedited removal.
Outcome: Temporary relief for specific, minor blockages, but may not address underlying deliverability issues.
Focus on root cause and overall deliverability
Approach: Identify and rectify the behaviors that led to the listing and improve overall sending practices.
Outcome: Sustainable long-term deliverability improvement and prevention of future blocklistings on all relevant lists.
Beyond SORBS: Proactive strategies for email deliverability
True email deliverability success lies in proactive strategies that build and maintain a strong sender reputation. Regardless of a SORBS listing, these practices are fundamental. A good list hygiene program, for example, is far more impactful than chasing down a single blocklist entry. This includes regularly cleaning your lists of inactive or invalid addresses, implementing double opt-in, and monitoring engagement.
Best practices for email deliverability
List hygiene: Regularly remove inactive subscribers and hard bounces from your lists. Invalid or old email addresses can turn into spam traps, leading to blocklistings.
Email authentication: Ensure your SPF, DKIM, and DMARC records are correctly configured and aligned. These protocols verify your sending authenticity and are critical for inbox placement.
Engagement monitoring: Monitor your open, click, and complaint rates. Low engagement and high complaint rates signal problems to mailbox providers, affecting your reputation.
Content quality: Avoid spammy content, excessive links, or misleading subject lines. Ensure your emails provide value to recipients.
By focusing on these broader aspects of email deliverability, you'll not only mitigate the impact of specific blocklistings but also build a robust sending program that consistently reaches the inbox. Remember, a listing on a blocklist (or blacklist) like SORBS is often a diagnostic hint, not the entire problem. Addressing the underlying health of your email program is what truly drives long-term success. For more insights on improving your deliverability, see our guide to technical solutions from top senders.
Prioritizing true deliverability
In summary, while a SORBS listing might appear alarming, it's often a lower-priority issue when compared to broader email deliverability challenges. My experience has shown that major mailbox providers generally do not heavily rely on SORBS for their filtering decisions. Instead of solely focusing on delisting, prioritize a comprehensive review of your email program.
The true path to consistent inbox placement involves understanding bounce messages, practicing rigorous list hygiene, ensuring strong email authentication, and maintaining positive sender reputation. By addressing these foundational elements, you'll build a resilient email program that minimizes spam folder placement and maximizes engagement, regardless of minor blocklist (or blacklist) entries.
Views from the trenches
Best practices
Always verify if a SORBS listing is genuinely impacting your delivery through bounce messages, rather than assuming it's the primary problem.
Prioritize overall email program health, including list hygiene and authentication, which will mitigate issues more effectively than single blocklist removals.
Measure true inbox placement, not just acceptance rates, to understand your actual deliverability performance.
Common pitfalls
Overestimating the impact of a SORBS listing on deliverability, especially to major mailbox providers.
Spending excessive time or money on delisting from SORBS without addressing the root cause of the listing.
Not differentiating between mail accepted by the server and mail actually reaching the inbox.
Expert tips
Focus on the underlying sending behaviors that lead to blocklistings, as fixing these will improve deliverability across all recipients.
For specific blockages at Proofpoint-hosted domains, a SORBS listing can sometimes be a direct factor.
Good list acquisition practices are crucial going forward, even if current deliverability seems acceptable.
Expert view
Expert from Email Geeks says: SORBS is not widely used, and if you are experiencing blocks at major providers like Yahoo, Gmail, or Microsoft, it is very unlikely that SORBS is the problem.
2021-08-11 - Email Geeks
Expert view
Expert from Email Geeks says: The underlying behavior that led to the SORBS listing is the true issue, and simply getting delisted will not resolve deliverability problems with major mailbox providers.
Spamhaus
0Spam
Cisco
NoSolicitado
URIBL
abuse.ro
ALPHANET
Anonmails
Ascams
BLOCKEDSERVERS
Calivent Networks
EFnet
JustSpam
Kempt.net
NordSpam
RV-SOFT Technology
Scientific Spam
Spamikaze
SpamRATS
SPFBL
Suomispam
System 5 Hosting
Team Cymru
Validity
www.blocklist.de Fail2Ban-Reporting Service
ZapBL
2stepback.dk
Fayntic Services
ORB UK
technoirc.org
TechTheft
Gmail, do not heavily rely on SORBS for their filtering decisions. 
Outlook and 
Gmail to get a clear picture.
