Why are SORBS listing timestamps missing and how to identify senders on SORBS?
Matthew Whittaker
Co-founder & CTO, Suped
Published 9 Jul 2025
Updated 19 Aug 2025
7 min read
For anyone involved in email deliverability, encountering a listing on the SORBS blocklist can be a significant setback. SORBS, or the Spam and Open Relay Blocking System, is a widely used DNS-based blocklist (DNSBL) that helps email providers filter out spam and protect their users. When your IP address or domain is listed, it signals to receiving mail servers that your emails might be unsolicited or originate from a compromised source, leading to bounces and missed inboxes.
One of the most frustrating aspects of troubleshooting a SORBS listing is the frequent absence or inaccuracy of timestamps on their public listings. Traditionally, these timestamps were crucial for identifying precisely when an IP or domain was added to the blocklist, which, in turn, helped pinpoint the exact sending incident that triggered the listing. Without this vital piece of information, diagnosing the root cause becomes a much more complex and time-consuming process.
This article delves into why SORBS listing timestamps may be missing, whether it is an intentional change or an unintended side effect of system updates, and, most importantly, how to identify the specific senders responsible for a listing when you lack this critical time-based data. Understanding these challenges and developing alternative identification strategies is key to maintaining optimal email deliverability, especially for those managing shared IP infrastructures.
The issue of missing or incorrect timestamps on SORBS listings has been a recurring concern within the email community. While there's no official statement from SORBS confirming an intentional removal of this data, it's widely speculated that these discrepancies often arise from system maintenance, database migrations, or other technical backend challenges. Community discussions suggest that these are unintended consequences rather than a deliberate effort to obscure information.
The impact of these missing timestamps is significant. Without a precise time of listing, it becomes incredibly difficult to correlate the blocklisting (or blacklisting) event with specific sending activities in your mail logs. This challenge is particularly acute for email service providers (ESPs) or organizations with shared IP addresses, where numerous clients or internal departments might be sending mail simultaneously from the same IP space.
A SORBS listing means your IP address or domain has been flagged, often due to spam, open relay activity, or compromised systems. While SORBS remains a relevant blocklist for some email providers, its impact on deliverability can vary. However, a listing still warrants investigation to maintain a healthy sender reputation.
This situation underscores the need for robust internal logging and proactive monitoring strategies that don't solely rely on external blocklist data for troubleshooting. While the absence of timestamps is a hindrance, it forces a more comprehensive approach to identifying and mitigating issues promptly.
Why identifying senders is crucial
Identifying the specific sender responsible for a SORBS listing is paramount, especially when operating shared email infrastructure. A single malicious or compromised sender can quickly degrade the reputation of an entire IP address, affecting all legitimate users. Without timely identification, the blocklist event can persist longer, causing widespread email delivery failures.
With timestamps
Pinpoint accuracy: You could quickly narrow down the incident to a specific hour or even minute, allowing direct correlation with your internal logs.
Faster resolution: Identifying the responsible party meant faster mitigation of the issue and quicker delisting.
Proactive measures: Historical data with timestamps helped in understanding patterns and implementing preventive measures.
Without timestamps
Broad search: You are forced to search through a much wider range of log data, which is resource-intensive and time-consuming.
Delayed resolution: The longer it takes to find the source, the longer the IP remains on the blocklist, impacting all senders.
Increased risk: Without clear data, it's harder to address vulnerabilities, potentially leading to repeat listings on blocklists like SNDS.
Maintaining a strong sender reputation is an ongoing effort. Every blocklist event, even minor ones, contributes to your overall reputation score. A prolonged listing due to an inability to identify the source can severely damage your standing with internet service providers (ISPs) and affect your email deliverability. Therefore, adapting your identification process to account for missing timestamps is essential for timely mitigation and reputation recovery.
The critical importance of swift identification is highlighted when dealing with shared IP infrastructure. Any blocklisting (or blacklisting) impacts every client using that IP, regardless of their own sending practices. This necessitates a proactive and efficient system for tracking and attributing email sending behavior.
Strategies for sender identification without timestamps
When timestamps are unavailable, your best course of action is to engage directly with SORBS. Many blocklist operators, including SORBS, are willing to provide redacted header information or other details about the offending email. This typically involves opening a support ticket and clearly explaining your need to identify the source of the spam to mitigate ongoing issues, especially if you manage shared IPs. The information provided might not be a full header, but it can often contain enough clues, such as subject lines, sender domains, or even partial recipient addresses, to narrow down your internal search.
Beyond direct communication, leveraging your internal email logs is critical. Even without a precise SORBS timestamp, you can use other indicators to narrow your search. Check recent DMARC reports, bounce messages received, or any other anomaly reports from the general timeframe of the listing. Once you have a broader time window, you can systematically review your mail server logs for unusual sending patterns, high volume bursts, or messages to known spam trap addresses.
Example mail log entry for a SORBS bounceplaintext
Jan 20 10:30:05 mailserver postfix/smtp[12345]: ABCD12345: to=<recipient@example.com>, relay=mail.isp.com[192.0.2.1]:25, delay=0.5, delays=0.05/0.01/0.1/0.34, dsn=2.0.0, status=sent (250 2.0.0 Ok)
Jan 20 10:30:06 mailserver postfix/smtp[12346]: BCDE23456: to=<spamtrap@example.org>, relay=mail.trap.com[198.51.100.1]:25, delay=0.6, delays=0.05/0.02/0.1/0.43, dsn=5.7.1, status=bounced (550 5.7.1 Service unavailable; Client host [YOUR_IP_ADDRESS] blocked using SORBS)
For ongoing vigilance, implement robust logging practices. Log everything possible about outbound emails, including the source IP address, the authenticated user (if applicable), the sender's email address, recipient addresses, subject lines, and even hashes of email bodies. This level of detail makes it far easier to backtrack and attribute activity, even when external blocklist data is lacking. Automate log analysis to flag suspicious patterns or high volumes from specific senders.
Data point
Why it's useful (without timestamps)
Source IP address
Essential for confirming your listed IP. Helps filter logs to relevant traffic.
Authenticated user/client ID
Directly links sending activity to a specific client account or internal system.
Sender email/domain
Helps identify specific campaigns or users sending problematic emails.
Recipient email addresses
Look for known spam traps or unusual recipient patterns. Some spam traps are known.
Volume of mail
Sudden spikes from a single sender can indicate a compromised account or spam activity.
Logging best practices
To effectively troubleshoot future blocklist issues, always ensure your email server logs are comprehensive and easily searchable. This includes maintaining logs for a sufficient historical period, ideally several weeks to months, and ensuring that each log entry contains detailed information about the sender, recipient, and the context of the email. This proactive approach significantly reduces the time and effort required to diagnose issues, even when external data like timestamps are missing.
By combining these strategies, you can piece together the puzzle of a blocklist listing, even when a crucial piece of information like a timestamp is absent. This diligent approach is fundamental to maintaining a high level of email deliverability and ensuring your legitimate emails reach their intended recipients.
Recovering from a SORBS listing
Navigating email blocklists (or blacklists), especially those with incomplete data like SORBS, requires a strategic and adaptable approach. While the absence of timestamps on SORBS listings undoubtedly complicates the troubleshooting process, it is not an insurmountable obstacle. The key lies in understanding the available alternatives and implementing robust internal practices.
Prioritizing direct communication with blocklist operators to obtain redacted header information, combined with meticulous internal log analysis, forms the backbone of effective sender identification. Proactive logging and monitoring of all outbound email activity are essential for rapidly pinpointing the source of any issues and preventing future blocklist occurrences.
By adopting these strategies, email deliverability professionals can continue to manage sender reputation effectively, ensuring that legitimate emails consistently reach the inbox, even when external blocklist data presents challenges.
Views from the trenches
Best practices
Maintain comprehensive logs that record detailed sender, recipient, and message metadata for all outgoing emails, including authenticated user IDs.
Regularly archive and store logs for extended periods to facilitate historical analysis during troubleshooting.
Establish direct communication channels with blocklist operators to request specific details about listings when public information is insufficient.
Implement automated monitoring for unusual sending patterns, sudden volume spikes, or suspicious recipient domains.
Conduct routine security audits to identify and address potential compromises of email accounts or systems.
Common pitfalls
Relying solely on external blocklist data (like timestamps) without having robust internal logging to corroborate information.
Not maintaining sufficient historical log data, making it impossible to investigate older listing events.
Failing to implement user authentication for sending, which makes it difficult to pinpoint the exact client causing issues on shared IPs.
Ignoring early warning signs from DMARC reports or bounce messages that could indicate emerging spam issues.
Not having a clear internal process for identifying and isolating problematic senders quickly.
Expert tips
Prioritize logging fields that link directly to a specific user or campaign, such as 'authenticated_user_id' or 'campaign_tag', in your mail server logs. This ensures that even if you can't find a timestamp, you can quickly identify the source.
Consider deploying a 'honeypot' email address that is not publicly known but is included in some lists. If mail is sent to this address, it immediately flags a potential issue, allowing you to trace back to the source internally.
Develop a playbook for blocklist incidents that outlines steps for communication with blocklist operators, internal log analysis, and remediation actions. This speeds up your response time.
Utilize unique internal identifiers for each client or campaign within your email platform. When an IP gets listed, you can cross-reference these identifiers with your logs, making it easier to pinpoint the exact source.
Regularly review your email sending policies and ensure all users are aware of acceptable use to prevent unintentional spamming behavior.
Marketer view
Marketer from Email Geeks says they have noticed that SORBS listing timestamps have been off since recent maintenance.
2018-10-22 - Email Geeks
Marketer view
Marketer from Email Geeks says that they mean the timestamps are completely gone, not just inaccurate.
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
Without clear data, it's harder to address vulnerabilities, potentially leading to repeat listings on blocklists like SNDS.
