Why are login verification emails not being received despite showing as delivered in logs?
Matthew Whittaker
Co-founder & CTO, Suped
Published 30 Jun 2025
Updated 19 Aug 2025
8 min read
It's a perplexing situation many email senders face: your logs show a login verification email as 'delivered,' yet the user insists they never received it. This isn't just a minor inconvenience, it directly impacts user experience, security, and ultimately, your business operations. The discrepancy between what your sending platform reports and what the recipient experiences highlights the complex journey an email takes after it leaves your server.
When an email service provider (ESP) or mail transfer agent (MTA) reports an email as delivered, it generally means the recipient's mail server accepted the message. However, this acceptance doesn't guarantee the email will land directly in the user's primary inbox. Instead, it might be subjected to further scrutiny by the recipient's security measures, often resulting in it being quarantined, junked, or even silently dropped.
I've encountered this scenario countless times, particularly with sensitive emails like login verification codes or password resets. The key to solving this puzzle lies in understanding what happens post-delivery and identifying the specific hurdles preventing your messages from reaching the intended recipients. Let's delve into the layers of email delivery to uncover why your login verification emails might be going astray.
The true meaning of 'delivered'
Understanding what 'delivered' truly means is fundamental. For most email service providers, 'delivered' signifies that the recipient's mail server has successfully acknowledged and accepted the email. This is typically indicated by a 250 OK status code during the SMTP conversation. Once this status is received, your sending platform no longer has control over the email's fate. It's now entirely in the hands of the recipient's mail infrastructure.
After acceptance, the email undergoes further processing by the recipient's system. This includes various anti-spam and security filters, internal routing rules, and user-specific configurations. As a result, an email can be accepted but still not appear in the primary inbox. It might be directed to a spam or junk folder, a promotions tab, a quarantine held by an IT administrator, or in rare cases, silently discarded. This is why you often hear users say, 'It's not in my spam folder either!'
The critical takeaway is that 'delivered' simply means the email reached the perimeter of the recipient's network. It doesn't equate to 'inbox placement.' For a deeper dive into this phenomenon, it's helpful to understand why emails sometimes show as delivered but not appearing in the inbox. Your sending logs, while helpful, offer only one piece of the puzzle.
Common culprits behind missing verification emails
Several factors can lead to login verification emails being accepted by a mail server but never seen by the end-user. It's often a combination of these elements rather than a single issue.
A common culprit is the recipient's spam filters, especially in corporate environments. Unlike personal email accounts, business domains often employ sophisticated email security gateways (e.g., Microsoft 365, Google Workspace, Proofpoint, Mimecast) that perform deep content scanning and reputation checks. These filters can quarantine or silently drop emails deemed suspicious, even if they passed initial delivery checks. Verification emails, due to their often generic subject lines and links, can sometimes trigger these filters more easily than regular marketing or transactional emails, even if they come from the same domain.
Content is another factor. Even if your domain's authentication (SPF, DKIM, DMARC) is perfectly configured, the email's content itself can trigger spam filters. Elements like suspicious links, generic phrasing, excessive capitalization, or even unoptimized image sizes can reduce your email's positive score. Since login verification emails are often plain text or simple HTML, they might lack the engagement signals that typically help marketing emails bypass filters.
Finally, issues with recipient-side settings, like specific user filters or folder rules, can also be at play. While less common for widespread issues, it's worth considering for individual cases.
Content vs. authentication
While strong SPF, DKIM, and DMARC are crucial for getting your email accepted by the receiving server, they don't guarantee inbox placement. A perfectly authenticated email can still land in spam or be quarantined if its content or sender reputation raises red flags.
Diagnosing the problem
To effectively troubleshoot, you need to go beyond your own sending logs. The real challenge is getting insights from the recipient's side. Here's how to start diagnosing the problem:
Check MX records: For the 'personalized' or custom domains experiencing issues, look up their MX records. This will tell you which mail service (e.g., Yahoo Mail, Outlook.com, a private server) or spam filter is handling their incoming mail. This helps identify commonalities among affected users.
Run inbox placement tests: Use a reliable email deliverability tester to send your login verification email template to seed addresses across various providers and corporate spam filters. This will show you exactly where your emails are landing (inbox, spam, promotions, or blocked).
Examine content differences: If other email types from the same domain are delivered, compare the login verification email's content (subject line, body text, links, image usage) against your successful email streams. Look for anything that could be perceived as suspicious or overly generic by spam filters.
Request recipient-side logs: If possible, ask affected users to contact their IT or email administrator for their mail server's logs. This is often the most direct way to pinpoint the exact reason for non-delivery post-acceptance. Look for specific error codes or explanations from the recipient's MTA.
Example MX record lookupBASH
dig MX example.com
This command, run from your terminal, will return the MX records for a given domain, revealing which mail servers handle its incoming email. For instance, if you see entries pointing to secureserver.net, you know the domain uses GoDaddy's email services, and you can focus your troubleshooting there.
Strategies for resolution
Once you have a clearer picture of why your login verification emails aren't reaching inboxes, you can implement targeted solutions. Often, it comes down to a blend of technical optimization and communication with affected users.
A good first step is to revisit your email authentication. Ensure your SPF, DKIM, and DMARC records are correctly configured and aligned, particularly for the domain used to send these transactional emails. Even minor misconfigurations can lead to emails being flagged, especially by strict corporate filters. You can use a DMARC record generator and DMARC monitoring to get insights into authentication failures.
Additionally, assess the content of your verification emails. Keep them concise, clear, and free of unnecessary formatting or images. Ensure all links are secure (HTTPS) and use recognizable branding. If many users are on the same corporate domain, you might need to advise them to whitelist your sending domain with their IT department. Consider segmenting your email streams if transactional emails are sent via a different IP or sub-domain than your marketing emails, to manage their respective reputations independently.
General email sends
Often includes marketing, newsletters, and general communication.
When your login verification emails are reported as delivered but aren't reaching users' inboxes, it's a frustrating but solvable problem. I've gathered some insights from other deliverability professionals facing similar issues:
Best practices
Always review the recipient's MX records to identify their mail service or spam filter.
Conduct regular inbox placement tests for critical transactional email streams.
Ensure SPF, DKIM, and DMARC are correctly configured and aligned for all sending domains.
Keep transactional email content as concise and clean as possible, with secure links.
Common pitfalls
Assuming 'delivered' in logs means 'inbox' for the end user.
Ignoring the specific content and sending patterns of transactional emails.
Not considering corporate-level spam filters that quarantine emails before reaching user inboxes.
Failing to differentiate between personal and corporate email domains in troubleshooting.
Expert tips
An expert from Email Geeks says that getting MTA logs from the recipient's side is the only way to get the full truth about delivery status.
An expert from Email Geeks notes that Outlook as a mail client typically does not apply filtering by default.
An expert from Email Geeks advises looking for commonalities among affected 'personalized' or custom domains by checking their MX records to identify shared mail services or spam filters.
An expert from Email Geeks suggests that if all other factors are constant, but the content of the problematic email stream is different, the content itself should be suspected as the cause.
Expert view
An expert from Email Geeks says checking the MTA's send log is crucial to confirm if a message was truly sent and accepted by the receiving server.
2024-01-08 - Email Geeks
Expert view
An expert from Email Geeks explains that an email might be delivered as far as the sender's ESP is concerned, but the receiving mail server could be quarantining it in a folder only accessible by an admin, not the user.
2024-01-08 - Email Geeks
Bridging the gap from 'delivered' to 'received'
The phenomenon of login verification emails showing as delivered but not received is a nuanced deliverability challenge. It requires looking beyond surface-level logs and understanding the intricate journey an email takes from sender to recipient inbox. By meticulously checking MX records, conducting inbox placement tests, optimizing content, and ensuring robust authentication, you can significantly improve the success rate of these critical communications.
Remember, 'delivered' is just the beginning of the story. The ultimate goal is inbox placement, especially for high-priority transactional emails that are vital for user access and security. Persistent effort and detailed investigation will help bridge the gap between reported delivery and actual user reception.
Microsoft 365, 
Google Workspace, Proofpoint, Mimecast) that perform deep content scanning and reputation checks. These filters can quarantine or silently drop emails deemed suspicious, even if they passed initial delivery checks. Verification emails, due to their often generic subject lines and links, can sometimes trigger these filters more easily than regular marketing or transactional emails, even if they come from the same domain.
Yahoo Mail, 
Outlook.com, a private server) or spam filter is handling their incoming mail. This helps identify commonalities among affected users.
secureserver.net, you know the domain uses GoDaddy's email services, and you can focus your troubleshooting there.
