What steps should I take when Gmail blocks my new IP address on SFMC?
Matthew Whittaker
Co-founder & CTO, Suped
Published 10 Jun 2025
Updated 17 Aug 2025
6 min read
Getting a new IP address blocked by Gmail in Salesforce Marketing Cloud (SFMC) early in your IP warm-up phase can be incredibly frustrating. It feels like you've done everything right: low volume, good sending practices, and all your authentication records (SPF, DKIM) are correctly configured. Yet, you're hit with a block.
This situation is more common than you might think, particularly with major inbox providers like Gmail, which are highly cautious about new IP addresses. Even with a new, clean IP, they prioritize protecting their users from potential spam. It is important to know that it is often not a fault of your own, but simply the nature of establishing trust with Gmail.
The key is to understand that initial blocks from Gmail on a new IP address in SFMC are typically not permanent. They are usually a signal for you to review your entire sending strategy, from technical setup to content and audience targeting, and make adjustments. Let's explore the steps you should take to resolve this issue and get your emails landing in the inbox.
Diagnosing the gmail block
When Gmail blocks your new IP address, the first step is to accurately diagnose the problem. The bounce message is your primary clue. Often, you might see a 5.7.1 delivery not authorized error with a note that the message is “likely unsolicited mail.” This specific error indicates that Gmail suspects your emails are unwanted, regardless of your intent.
To obtain more detailed information about the rejection, you can often find specifics within SFMC's _Bounce data view, which provides raw SMTP rejection messages. Salesforce support can also help in providing these detailed bounce logs if you are unable to access them. This precise feedback is essential for targeted troubleshooting.
Additionally, leverage Google Postmaster Tools (GPT). If you haven't set it up, do so immediately. GPT provides invaluable data on your domain and IP reputation from Google's perspective, including spam rates, IP reputation, and domain reputation. While the data can sometimes be opaque, it often offers critical insights into how Gmail perceives your sending behavior.
Understanding the 5.7.1 error
The error message 5.7.1 (delivery not authorized) [IP Redacted] Gmail has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked. For more information, go to https://support.google.com/mail/?p=UnsolicitedMessageError indicates that Gmail's spam filters have flagged your content or sender reputation as suspicious. This is not typically a permanent block but a strong signal to re-evaluate your email practices, focusing on content, sender authenticity, and audience engagement to improve your standing.
Ensuring strong technical foundations
Even if you believe your SPF and DKIM are correctly configured, it's crucial to double-check every technical aspect. In Salesforce Marketing Cloud, your Sender Authentication Package (SAP) domain must be fully implemented. This includes ensuring your custom return-path domain matches your From domain. Any mismatch can lead to deliverability issues.
Confirming your DKIM signatures are passing is also paramount. Use an email deliverability testing tool to verify that your emails are properly signed and that the signatures are visible and valid to mail servers. Incorrect or missing DKIM can severely impact your sender reputation, especially with a new IP. Ensure that SPF is also configured correctly and aligning.
For SFMC users, if you are sending through private domains in addition to your SAP domain, ensure that SPF, DKIM, and DMARC records are correctly implemented for each. Misconfigurations can lead to confusing domain reputations and deliverability challenges. If SPF is not aligned, it could be confusing for receiving servers.
Correct SAP configuration
Return-Path Alignment: Your custom return-path domain should match your From domain exactly.
DKIM Signing: All emails must be signed with DKIM, and the signature should pass verification checks.
SPF Configuration: Ensure your SPF record includes all authorized sending IPs for your domain, including Salesforce Marketing Cloud.
Domain Mismatch: Sending from a domain that does not align with your SAP setup.
Missing DKIM: Emails are not digitally signed, or the signature is invalid.
Incorrect SPF: SPF records are not updated to include the new IP, leading to SPF unauthorized mail errors.
SSL Certificates: Missing SSL certificates on image-hosting domains can contribute to blocks.
Optimizing content and audience strategy
When Gmail says your messages are likely unsolicited, it is a strong indication that your content or audience strategy needs adjustment. Even if your list is legitimately acquired, Google's algorithms might detect patterns associated with spam. This is especially critical during IP warm-up, where even minor issues can lead to significant blocks.
Review your email content for anything that might trigger spam filters. This includes excessive imagery, too many links, or language commonly used in unsolicited mail. While it might seem like your content is nothing phishy, automated filters look for specific indicators. Aim for clean, balanced content with a clear call to action.
Crucially, during IP warm-up, you must target your most engaged audience segments. Sending to recipients who have recently opened or clicked your emails demonstrates positive engagement, which helps build a strong sender reputation. Gradually increase your sending volume to these engaged users before expanding to broader segments.
Finally, ensure strict list hygiene and proper segmentation. Data errors or segmentation failures can lead to sending to inactive or unengaged addresses, quickly eroding your new IP's reputation. Regularly clean your lists to remove bounces and inactive users, and always honor unsubscribe requests promptly.
Recovery and continuous monitoring
In many cases, an initial Gmail block on a new IP during warm-up can resolve itself within a day or two if you pull back on volume and maintain consistent, good sending practices. Gmail is often cautious with new IPs due to lack of established history. Persistence and adherence to best practices are key.
While immediate blocks can be frustrating, avoid drastic changes that might further destabilize your reputation. Instead, focus on small, consistent improvements. Only after exhausting internal troubleshooting and technical checks should you consider reaching out to Google directly via their sender contact forms. Be prepared to provide comprehensive details about your sending practices and efforts to comply with their guidelines. Continuous blocklist monitoring (or blacklist monitoring) and performance analysis are crucial to maintaining healthy deliverability moving forward.
Patience and persistence are vital
New IPs inherently lack sender reputation. Gmail's strict filtering on unknown IPs means you might experience temporary blocks (or blacklists) even with legitimate sending. Don't panic. Reducing volume slightly and maintaining good practices often resolves these transient issues as Gmail's systems learn and trust your sending patterns. Avoid immediate large-scale changes to your sending infrastructure or volume unless a clear technical misconfiguration is identified.
Views from the trenches
Best practices
Actively use Google Postmaster Tools to monitor your IP and domain reputation with Gmail.
Segment your audience to prioritize sending to your most engaged subscribers first during IP warm-up.
Ensure your SAP domain is fully implemented, with matching return-path and From domains.
Verify all emails are properly DKIM-signed and pass authentication checks using email testing tools.
Common pitfalls
Panicking and making drastic changes to your sending strategy after an initial block.
Ignoring bounce messages and not analyzing the specific SMTP rejection codes.
Sending to unengaged or old segments of your list during the crucial IP warm-up phase.
Assuming authentication is correct without regular verification using third-party tools.
Expert tips
It is often not a content issue unless a specific content violation is evident, focus on IP reputation.
Check for segmentation failures and data errors that could be leading to sending to incorrect recipients.
Be patient, as new IPs will often encounter initial caution from Gmail due to a lack of sending history.
Consider engaging an email deliverability consultant if issues persist despite internal efforts.
Expert view
Expert from Email Geeks says a content block on a new IP is rare and suggests examining the actual rejection message for more clarity, as it may not be primarily an IP issue.
June 20, 2024 - Email Geeks
Marketer view
Marketer from Email Geeks says they would want more information about the rejection, recommending asking support for raw SMTP rejection or bounce messages.
June 21, 2024 - Email Geeks
Moving forward after a Gmail block
Facing a Gmail block on a new IP address in Salesforce Marketing Cloud is a challenge many email marketers encounter. The initial shock of an unsolicited mail message can be unsettling, but it is rarely a sign of irreparable damage. Instead, it is an opportunity to fine-tune your email program and reinforce your sender reputation.
By diligently diagnosing the issue through bounce messages and Postmaster Tools, ensuring all technical configurations are flawless, optimizing your content and audience strategy, and exercising patience during the recovery period, you can overcome these initial hurdles. Remember, building a strong sender reputation takes time and consistent effort. Embrace these challenges as learning experiences to foster robust and reliable email deliverability.
Gmail in Salesforce Marketing Cloud (SFMC) early in your IP warm-up phase can be incredibly frustrating. It feels like you've done everything right: low volume, good sending practices, and all your authentication records (SPF, DKIM) are correctly configured. Yet, you're hit with a block.
Salesforce Marketing Cloud, your Sender Authentication Package (SAP) domain must be fully implemented. This includes ensuring your custom return-path domain matches your From domain. Any mismatch can lead to deliverability issues.
