What to do when a customer says they aren't receiving marketing emails even after safelisting?
Michael Ko
Co-founder & CEO, Suped
Published 28 Apr 2025
Updated 16 Aug 2025
6 min read
It's a familiar scenario for email marketers: a customer reaches out, complaining they haven't received your marketing emails, despite being on your list and, in this specific case, even after their IT team confirmed safelisting your domain. Your email service provider (ESP) dashboard shows the emails as "sent" successfully. So, what exactly is going on, and how can you help them fix it?
The critical distinction here lies between an email being "sent" and an email being "accepted" by the recipient's mail server. When your ESP reports an email as "sent," it typically means it has successfully handed the message off to the next server in the delivery chain. It doesn't, however, guarantee that the recipient's server fully embraced the email or placed it directly into their inbox.
This situation often points to a filtering issue on the recipient's end, even with safelisting in place. My approach is to gather as much specific data as possible from my sending platform and then equip the customer's IT team with that information to trace the email within their own infrastructure. It's a collaborative effort to solve what can be a very elusive deliverability challenge.
Validating true email acceptance
The first step is to go beyond what your email service provider (ESP) reports as "sent." A "sent" status often only confirms that the email left your ESP's servers successfully. It doesn't guarantee it was truly accepted by the recipient's mail server or reached their inbox.
You need to confirm if the email was accepted by the recipient's mail server. This typically involves reviewing SMTP transaction logs. If your ESP doesn't provide these logs directly, you'll need to open a support case with them to request the specific delivery details for the affected emails.
These logs will show the SMTP replies, indicating whether the receiving server accepted the email, rejected it, or issued a temporary error (soft bounce). This is critical information to share with the customer's IT team.
Essential information to request
SMTP logs: Request full SMTP transaction logs for the specific emails in question, including timestamps, message IDs, and the final SMTP reply code from the recipient's server.
Hard bounces: Confirm if there were any hard bounces for the recipient's email address in your ESP's suppression list. You can find more details if a user's email hard bounced and they aren't receiving emails.
Suppression list: Check if the customer's email address or domain has been added to a global or enterprise-wide suppression list within your ESP, as some platforms might share these.
Working with the recipient's IT
Once you have the SMTP transaction logs, confirming acceptance or providing a specific error, you can provide this crucial data to the customer's IT team. This shifts the focus from your sending platform to their receiving infrastructure. They are in the best position to trace the message once it enters their system.
Even if safelisting is in place, emails can still be quarantined, marked as spam, or routed to other folders based on internal rules or more advanced threat detection systems. Safelisting typically bypasses basic spam filters but doesn't guarantee direct inbox placement. For instance, a recipient might move emails from a "junk" folder into their primary inbox, which helps inform the inbox where to place that email in the future. See this guide on contacts not receiving marketing emails for more.
Ask their IT team to check their internal mail logs for the specific message ID and timestamp you provide. This allows them to see what happened to the email after their edge server accepted it. It's not uncommon for emails to be accepted and then silently dropped or quarantined.
Sample successful SMTP transaction log entryplain
250 2.0.0 OK 1234567890-abcdef-12345 message accepted for delivery
Scenario 1: Email accepted, not received
If your ESP confirms the email was accepted (250 OK SMTP reply), the issue lies within the recipient's email system. Their internal mail server or security solutions might be:
Quarantining: Holding the email for manual review.
Internal filtering: Applying rules that move the email to a different folder.
Post-acceptance rejection: Silently dropping the email based on advanced content scanning.
Scenario 2: Email not accepted
If your ESP's logs show a rejection or temporary failure, the issue is with the recipient's mail server or network configuration. This could be due to:
IP blocklist: Your sending IP is on a private blocklist (blacklist) at their end.
DNS issues: Problems resolving your domain's DNS records, preventing delivery.
Mailbox full/inactive: The recipient's mailbox might be over quota or no longer active, leading to a hard bounce.
Exploring deeper deliverability issues
Safelisting (or whitelisting) usually means adding your sending IP addresses or domain names to a trusted list. However, it may not cover all aspects of email filtering, especially those related to content, sender reputation, or evolving security policies. Sometimes, even with a safelist, specific email content, attachments, or links can trigger advanced filters. This is why it's important to understand how to determine if marketing emails are going to spam.
Your sender reputation also plays a significant role. Even if a domain is safelisted, a poor sender reputation at an individual inbox provider (ISP) level could lead to messages being filtered. Monitoring your domain reputation through tools like Google Postmaster Tools (for Gmail recipients) or other postmaster pages (e.g., for Microsoft Outlook) can provide insights into potential issues.
It's also worth checking if the customer has any personal email rules or filters set up in their email client that might be redirecting or deleting your messages. Sometimes, users inadvertently create rules that affect incoming mail. Ask them to check their junk, spam, and other custom folders. This is a common occurrence, as highlighted by some discussions like those on HubSpot's troubleshooting guides.
Category
Explanation
Action for Recipient IT
Action for Sender
Recipient-side filters
Internal security appliances or rules are flagging emails post-acceptance.
Check internal mail logs for message ID, look for quarantine or junk folder routing.
Provide SMTP logs and message ID. Review email content for potential triggers.
Personal email rules
Customer has set up rules in their email client that move or delete emails.
N/A
Ask customer to check personal settings and other folders.
IP/domain blocklist
Your sending IP or domain is on a specific blocklist (blacklist) maintained by the recipient's organization or ISP. This can happen even if your domain is safelisted for other reasons, if you're on a private blocklist for example. Learn more about email blacklists and how they work.
Check their internal blocklists (blacklists) or security appliance reports.
Check public blocklists (blocklists) using a blocklist checker. Work with recipient IT to get off their internal list. You can use blocklist monitoring to stay on top of this.
Sender reputation
Even if your domain is safelisted, low sender reputation at the mailbox provider level can lead to filtering.
N/A
Monitor Google Postmaster Tools and other postmaster pages, like those for Microsoft Outlook. Improve sending practices to boost email deliverability rates.
Proactive steps and preventative measures
To minimize such issues in the future, it's crucial to maintain excellent sending practices. This includes regularly cleaning your email lists, ensuring proper email authentication (SPF, DKIM, DMARC), and monitoring your deliverability rates. A solid DMARC monitoring setup can provide aggregate reports that highlight where your emails are failing authentication or being rejected, offering valuable insights.
Educating your customers on checking their spam or junk folders, and how to mark legitimate emails as "not spam" is also important. This user action can significantly improve future inbox placement by training their personal email filter.
Implement a comprehensive deliverability strategy that includes regular email deliverability tests and careful segmentation. Understand that even legitimate emails can be blocked by major ISPs despite passing DMARC, SPF, and DKIM, due to other factors like content or sending volume.
Continuous improvement checklist
Monitor DMARC reports: Actively use DMARC monitoring to gain visibility into email authentication failures and rejections across various mailbox providers.
Maintain list hygiene: Regularly remove inactive or bouncing addresses to protect your sender reputation.
Segment intelligently: Tailor your sending volume and content to recipient engagement, reducing the likelihood of spam complaints.
Ensure you are getting SMTP transaction logs from your ESP to verify acceptance, not just 'sent' status, as this is crucial for troubleshooting.
When a customer reports missing emails, always offer to send a test email to their IT team directly to get a specific transaction to investigate.
Provide the recipient's IT team with message IDs and timestamps to help them trace the email within their internal systems once it has been accepted.
Common pitfalls
Relying solely on your ESP's 'sent' status without confirming acceptance by the receiving server can lead to misdiagnosed deliverability issues.
Underestimating the impact of private, internal blocklists (blacklists) maintained by recipient organizations, even when public safelisting is in place.
Assuming that safelisting guarantees inbox delivery, as internal rules or advanced filters can still quarantine or misroute emails after acceptance.
Expert tips
Push your ESP's support team for full SMTP replies. It is their responsibility to provide this data to help you troubleshoot.
Remind customers to check all their folders, including spam, junk, and any custom folders, as personal email client rules can often redirect legitimate emails.
If the recipient's edge server accepts the email, but it doesn't reach the inbox, technically, the responsibility shifts to the recipient's email system as per RFCs.
Expert view
Expert from Email Geeks says that getting the actual transaction logs is pretty crucial, as you need to know where the failure is happening.
2023-03-22 - Email Geeks
Expert view
Expert from Email Geeks says that the only fix is to get the SMTP transaction logs and see if the recipient domain is accepting emails.
2023-03-22 - Email Geeks
Resolving elusive deliverability challenges
When a customer isn't receiving marketing emails despite safelisting, it's a frustrating but solvable problem. The key is to move beyond the simple "sent" status and dive into the specifics of SMTP transaction logs. This level of detail is often what enables you to pinpoint the exact point of failure.
By collaborating closely with the recipient's IT team and providing them with concrete data like message IDs and timestamps, you empower them to pinpoint where the email is getting lost within their own infrastructure. This investigative approach is often the fastest path to resolution.
Beyond individual troubleshooting, a robust and proactive deliverability strategy, focusing on authentication, reputation, and continuous monitoring, will significantly reduce such occurrences. This ensures your valuable marketing messages reach the intended inboxes and avoid unexpected filtering.
Google Postmaster Tools (for Gmail recipients) or other postmaster pages (e.g., for 
Microsoft Outlook) can provide insights into potential issues.
