Summary
SURBL (Spam URI Realtime Blocklist) and similar URL reputation services identify websites in unsolicited messages, impacting email deliverability by potentially causing emails to be marked as spam or blocked. Maintaining good list hygiene is crucial to avoid SURBL listings. Best practices include implementing double opt-in, cleansing lists of typo traps, and maintaining a suppression list. Proactively monitoring for blocklist listings and addressing issues promptly is key. Gradual IP warm-up, high engagement rates, and a strong sender reputation further reduce the risk of SURBL listings. While some believe bad list hygiene primarily leads to other deliverability problems indirectly causing SURBL issues, immediate investigation and corrective actions are necessary if a listing occurs.
Key findings
- SURBL Impact: SURBL listings negatively impact email deliverability, potentially leading to spam folder placement or blocking.
- Importance of List Hygiene: Maintaining good list hygiene is crucial for avoiding SURBL listings.
- Opt-In Practices: Implementing double opt-in ensures that only legitimate subscribers are added, reducing spam traps.
- Proactive Monitoring: Regular monitoring for blocklist listings helps identify and resolve deliverability issues promptly.
- Sender Reputation: Building and maintaining a strong sender reputation through engagement and proper sending practices reduces SURBL risk.
- Domain Reputation: Domain reputation is directly influenced by SURBL listings; a poor reputation can lead to spam filtering.
Key considerations
- Address Acquisition: Prioritize double opt-in to ensure valid and engaged subscribers.
- List Maintenance: Regularly cleanse lists of invalid addresses, typo traps, and unsubscribed users.
- Engagement Strategies: Focus on strategies to increase email engagement (opens and clicks) to improve deliverability.
- IP Warm-up: Gradually warm up new IP addresses to establish a positive sending reputation.
- Remediation Plan: Develop a plan to investigate, correct, and request delisting if your domain is SURBL-listed.
What email marketers say
10 marketer opinions
SURBL (Spam URI Realtime Blocklist) listings can significantly harm email deliverability by causing emails to be marked as spam or blocked. Maintaining good list hygiene is crucial to avoiding SURBL listings, including removing invalid email addresses, using double opt-in (COI/DOI), cleansing lists of typo traps, and maintaining a suppression list. Monitoring email deliverability for blocklist listings helps address issues promptly. Gradual IP warm-up and high engagement rates can improve sender reputation and reduce the risk of SURBL listings. If listed, investigate the cause and contact SURBL with evidence of corrective actions.
Key opinions
- Impact of SURBL: SURBL listings can negatively impact email deliverability by causing emails to be marked as spam or blocked.
- List Hygiene: Good list hygiene, including removing invalid emails and using double opt-in, is essential to avoid SURBL listings.
- Monitoring: Regularly monitoring email deliverability for blocklist listings helps identify and address issues promptly.
- Engagement: High email engagement rates (opens, clicks) improve deliverability and reduce the risk of SURBL listings.
- Proactive Measures: Gradually warming up IP addresses helps establish a positive sending reputation, avoiding SURBL listings.
- List Cleansing: Cleansing lists of typo traps reduces the chance of hitting spam traps, which can lead to SURBL listings.
Key considerations
- List Acquisition Practices: Implement double opt-in to ensure only legitimate subscribers are added to your list.
- Suppression Lists: Maintain a suppression list to avoid sending emails to unsubscribed or bounced addresses.
- Remediation: If listed on SURBL, investigate the cause, take corrective actions, and contact SURBL for delisting.
- Community consensus: Bad list hygiene will lead to deliverability problems, which may not be directly correlated to the SURBL listing itself.
Marketer view
Email marketer from Email Hippo shares that maintaining a suppression list of unsubscribed or bounced email addresses is crucial. Sending emails to these addresses can lead to increased spam complaints and potential SURBL listings.
24 Sep 2021 - Email Hippo
Marketer view
Email marketer from SendGrid shares that gradually increasing your sending volume when using a new IP address (IP warm-up) helps establish a positive sending reputation with ISPs, reducing the likelihood of being flagged as spam and listed on SURBL.
8 May 2023 - SendGrid
What the experts say
4 expert opinions
SURBL listings can negatively impact email deliverability due to trap hits from single opt-in ESP customers causing spam folder delivery. Maintaining a good domain reputation and list quality are crucial for avoiding SURBL listings. It is recommended to remove old, inactive, and invalid email addresses from your list to prevent sending to spam traps. For small senders, implementing confirmed opt-in (COI) or double opt-in (DOI) is also recommended.
Key opinions
- SURBL Impact: SURBL listings can cause spam folder delivery due to trap hits.
- Domain Reputation: Domain reputation directly influences deliverability; poor reputation leads to spam filtering.
- List Quality: Maintaining list quality by removing old, inactive, and invalid addresses avoids spam traps.
- Opt-In Methods: Confirmed opt-in (COI) or double opt-in (DOI) is recommended for small senders to mitigate SURBL issues.
Key considerations
- List Management: Regularly clean your email list to remove inactive and invalid addresses.
- Opt-In Strategy: Implement double opt-in or confirmed opt-in processes, especially for smaller senders.
- Reputation Monitoring: Monitor your domain reputation to quickly address any issues related to SURBL listings.
Expert view
Expert from Spam Resource explains that domain reputation directly influences deliverability. A poor domain reputation, potentially caused by SURBL listings, leads to more emails being filtered as spam or blocked.
28 Feb 2022 - Spam Resource
Expert view
Expert from Email Geeks recommends confirmed opt-in (COI) or double opt-in (DOI) for small senders due to SURBL.
5 May 2022 - Email Geeks
What the documentation says
5 technical articles
SURBL is a blocklist of websites found in unsolicited messages used by email administrators and anti-spam systems to identify and filter spam. Services like Spamhaus and Proofpoint use SURBL data or similar URL reputation services to block spam and improve deliverability. URIBL lists domains appearing in unsolicited bulk email, indicating a high probability of spam. Sender reputation, as tracked by systems like Cisco Talos, is critical for email deliverability, and negative reputation from SURBL listings can lead to emails being blocked or sent to the spam folder.
Key findings
- SURBL Purpose: SURBL identifies websites in unsolicited messages to help filter spam.
- Integration in Anti-Spam Systems: Anti-spam systems integrate SURBL data to block spam and improve deliverability.
- URL Reputation Services: URL reputation services identify malicious URLs to block spam and phishing emails.
- Listing Criteria: Domains listed by URIBL appear in unsolicited bulk email, indicating a high probability of spam.
- Sender Reputation Impact: Negative sender reputation, influenced by SURBL listings, leads to email blocking or spam filtering.
Key considerations
- Proactive Monitoring: Monitor your domain's presence on blocklists like SURBL.
- Spam Prevention: Implement practices to prevent your domain from being associated with unsolicited messages.
- Reputation Management: Maintain a positive sender reputation to ensure emails are delivered successfully.
Technical article
Documentation from URIBL explains that they list domains based on their appearance in unsolicited bulk email (UBE). They focus on identifying patterns of spam activity, and listings indicate a high probability of spam origin.
6 Aug 2024 - URIBL.com
Technical article
Documentation from Spamhaus explains that they use a variety of blocklists, including some that incorporate SURBL data, to block spam and improve email deliverability for legitimate senders. They actively track and list domains found in spam emails.
15 Jul 2024 - Spamhaus
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Besides Spamhaus, what blocklists are important for email marketers to monitor?
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How to contact SURBL and what are their policies regarding delisting and support for ESPs?
