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FAQs - Why is my IP address or domain blocklisted?

💡 Información relevante
This article is for users on a dedicated IP. If you're on a shared IP and believe it has been blocklisted, contact our support team for further investigation.

What is a blocklist?

A blocklist is a collection of IP addresses or domain names that Internet Service Providers (ISPs) or anti-spam solutions because they are suspected of engaging in suspicious activities, such as spamming, phishing, or generating high hard bounce, unsubscribe, complaint, or spam trap rates. When your IP address or domain name appears on a blocklist, it means it has been flagged as potentially harmful.

Hay dos tipos de listas bloqueadas:

  • ISP blocklist
    If an Internet Service Provider (ISP) blocklists your IP address or domain, emails sent to addresses using that ISP’s domain (e.g., gmail.com or outlook.com) will soft bounce.
  • Anti-spam blocklist
    Anti-spam solutions are commonly used by businesses and professionals to provide an additional layer of protection against spam. If an anti-spam solution blocklists your IP or domain, emails will soft bounce when sent to recipients using that solution.

Why is an IP address or domain blocklisted?

Most of the time, an IP address or domain is blocklisted because they are suspected of engaging in suspicious activities, such as spamming, phishing, or generating high hard bounce, unsubscribe, complaint, or spam trap rates.

Expand the following accordions to view some of the most common reasons why this might happen:

Es posible que esté enviando emails no solicitados

The most common reason for being blocklisted is that ISPs flag your emails as unsolicited or spam. This can happen if:

  • Your content appears spammy.
  • You’re sending to purchased or outdated contact lists.
  • Your recipients mark your emails as spam.
You are sending to unengaged or inactive contacts

Make sure you send emails to engaged contacts who have explicitly agreed to receive your communications. This helps generate positive metrics like opens, clicks, forwards, and replies while reducing the risk of spam traps, unsubscribes, hard bounces, and complaints.

Your bounce or complaint rates are too high

ISPs monitor bounce rates and spam complaints. If too many of your emails are rejected or reported as spam, your sending reputation may be negatively impacted, leading to your IP address or domain being blocklisted.

💡 Información relevante

Some ISPs, like Gmail and Yahoo, have a complaint threshold of 0.3%, meaning even a small number of complaints can negatively impact your sender reputation.

You did not properly warm up your dedicated IP
❗️ Importante
If you haven't sent emails from your dedicated IP in the last 30 days, you need to restart the warm-up process.

ISPs may blocklist your IP if you send too many emails too quickly from a new or inactive dedicated IP. Proper warm-up builds your reputation as a trusted sender.

To learn more, check our dedicated article Warm up your dedicated IP.

You're sending emails to spam traps

Spam traps are email addresses used to identify spammers and senders who don’t follow best practices. Sending emails to these addresses can lead to blocklisting.

To learn more, check our dedicated article What are spam traps and how to avoid them?.

You have been blocklisted by mistake

Even if you follow best practices, your IP address or domain may still be mistakenly blocklisted. This sometimes happen when an IP is flagged for suspicious activity, leading to similar IPs or domains being blocklisted as well.

💡 Información relevante

Some ISPs, such as Microsoft, are more sensitive to false positives and may blocklist new IPs even if they have a good sender reputation.

How do I know if my IP address or domain is blocklisted?

If your IP address or domain is blocklisted, you will typically notice a high number of soft bounces from a specific domain in Brevo. To confirm whether your IP or domain has been blocklisted, you should:

Step 1: (Optional) Use an external tool to scan against blocklists

❗️ Importante

Not all blocklists are listed in these external tools. Major providers like Gmail and Yahoo have private blocklists that won’t appear in public databases. You should still follow steps 2 and 3 to get more detailed information about your blocklist status.

If you want to quickly check, or as part of your regular deliverability routine, you can use an external tool to scan major and minor blocklists. Several online tools offer a quick overview:

Step 2: Check your campaign report in Brevo for soft bounce details

From Campaigns > Statistics, open a campaign report and access the Deliverability tab to view detailed information about soft bounces:

deliv_blocklist_deliverability-tab_soft-bounces_en-us.png

  1. Soft bounce statistics
  2. Soft bounce reasons
    Understand why your emails soft-bounced. If you see "The domain or IP blocklisted", it means your IP or domain has been blocklisted.
  3. Soft bounces by domains
    Identify which domains caused a high number of soft bounces.
    ❗️ Importante
    The Deliverability breakdown by domains feature is only available on Marketing Platform - Business and Enterprise plans.

Step 3: Check the error messages associated with the soft bounces

When an email soft bounces, the ISP returns an error message. You can review these messages to identify who blocklisted your IP address or domain and request removal.

  1. From Campaigns > Statistics, open a campaign report and access the Deliverability tab.
  2. In the Deliverability details section of a campaign report, click View next to the Soft bounces statistic. The list of contacts whose emails resulted in a soft bounce opens.
    deliv_blocklist_deliverability-tab_soft-bounces_view_en-us.png
  3. (Optional) In the search bar, enter the name of the domain that caused a high number of soft bounces. This helps filter results to find bounces related to blocklists.
    deliv_blocklist_soft-bounces_contacts_en-us.png
  4. Click a contact from the list to access their details.
  5. Under the Email event of the email that bounced, click Show details. If the bounce is due to a blocklist, the message often includes terms like "blocklist" or "banned IP" and may provide a direct link to request removal. For example, here’s an error message from Microsoft:
    deliv_blocklist_soft-bounce_microsoft_error-message_en-us.png

How can I get removed from a blocklist?

❗️ Importante
Solicitar a un proveedor de servicios de Internet o a una solución antispam que quiten tu IP o dominio de su lista bloqueada no garantiza que se haga.

Blocklisting reasons vary by IP address or domain, so there is no universal removal process.

Expand the following accordions to view our general best practices and specific guidance if you're blocklisted by Microsoft or Gmail:

General best practices

Before requesting removal from a blocklist, identify the root cause and take corrective actions:

  1. Identify the root cause
    • When did the issue start?
    • Are you sending from a new IP address or domain?
    • Have you recently increased your sending volume?
    • Are you receiving high complaint rates, hard bounces, or unsubscribe?
    • Are you sending emails to new or unengaged contacts?
  2. Fix the issue
    • Stop sending emails to blocked ISPs or recipients using the anti-spam solution that blocklisted you. Continuing to send to these recipients can further damage your sender reputation and delay the delisting process.
    • Improve contact segmentation to only send to engaged recipients.
    • Clean your contact list by removing inactive or unengaged users.
    • Warm up your IP again if you took a break from sending.
    • Reduce your sending volume and gradually rebuild your reputation.
Microsoft (hotmail.com, outlook.com, msn.com, live.com, onmicrosoft.com, Microsoft Office 365 custom domains)
  1. Follow the general best practices above ⬆️
  2. Send a small test campaign
    Start with an email campaign to 3,000 non-Microsoft contacts to demonstrate improved sending practices.
  3. Request mitigation from Microsoft
    Check the soft bounce error messages you received and submit a delisting request using the appropriate portal:
    Error message Type Delisting portal
    deliv_blocklist_soft-bounce_microsoft_b2c_error-message_en-us.png Microsoft Office 365 (B2B contacts)

    Office 365 Anti-Spam IP Delist Portal
    deliv_blocklist_soft-bounce_microsoft_error-message_en-us.png Microsoft (B2C contacts) OLC Support Form
  4. Check Microsoft's automatic response
    Once you submit your request, Microsoft will send an automatic response stating that they will either:
    1. Remove your IP from the blocklist.
    2. Clarify that your IP is not blocklisted on their end.
    3. Refuse to unblock your IP.
  5. Follow up with Microsoft if needed
    If you receive response #2 or #3, continue engaging with Microsoft by providing detailed information about:
    • The type of emails you send.
    • Your target audience and how you collect contacts.
    • The content of your emails.
    • Why you believe the blocklisting is a false positive.
      💡 Información relevante
      The more specific details you provide, the better your chances of getting delisted. Be as clear and detailed as possible about your sending practices.
  6. Resume sending in small batches
    Once you’ve addressed any sending issues and your metrics have improved, gradually start sending emails to Microsoft recipients again. We recommend you begin with small batches, targeting only your most engaged subscribers.
  7. (Optional) Sign up for Microsoft SNDS and JMRP Programs
    These Microsoft programs provide insights into your IP reputation and notify you when users mark your emails as spam. They can help you monitor and improve your email deliverability at Outlook.com. To learn more, check Microsoft's documentation.
Gmail (googlemail.com, gmail.com)
  1. Follow the general best practices above ⬆️.
  2. Request mitigation from Gmail
    Submit a delisting request using Gmail's Sender Contact Form.
  3. Resume sending in small batches
    Gmail does not provide direct responses to delisting requests, but they review submissions and take action as needed. Once you’ve addressed any sending issues and your metrics have improved, gradually start sending emails to Gmail recipients again. We recommend you begin with small batches, targeting only your most engaged subscribers.
  4. (Optional) Sign up for Google Postmaster Tools
    This tool provides insights into the emails you send to personal Gmail accounts, as well as the domains and IPs you use. To learn more, check Gmail's documentation.

How to avoid being blocklisted again?

After your IP or domain is removed from a blocklist, it’s important to follow best practices to prevent future issues and maintain a good sender reputation. Here are some essential steps to keep your email deliverability healthy:

  • Follow our best practices for managing a dedicated IP to maintain optimal inbox placement and maintain a strong reputation.

  • Send emails only to contacts who have explicitly subscribed and expect to hear from you.
  • Segment your contacts based on their interests to send relevant content and increase engagement.
  • Regularly clean your contact list to remove unengaged or invalid email addresses.
  • Encourage your recipients to add your email address to their address book, which helps your emails be seen as personal communication by ISPs.
  • Avoid using URL shorteners as they are commonly associated with spammers and can affect deliverability.
  • Regularly check your blocklist status to ensure you’re not on a blocklist.
  • Warm up your IP again if you’ve taken a break from sending, and gradually increase sending volume to rebuild your reputation.

By consistently following these practices and monitoring your metrics, you can reduce the risk of getting blocklisted in the future.

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