The issue of login verification emails not being received despite logs showing delivery is complex, involving factors on both the sending and receiving ends, as well as content and authentication issues. Experts and marketers emphasize checking MTA logs, recipient-side spam filters and configurations, and MX records to identify filtering systems. Content triggering spam filters, poor sender reputation, lack of user engagement, greylisting, delayed filtering rules, suppression lists, authentication problems (SPF, DKIM, DMARC), blocklisting, and custom recipient filters all contribute to this problem. Proactive measures such as seedlisting, maintaining a clean email list with explicit permissions, and carefully monitoring sender reputation are essential for ensuring reliable delivery.
15 marketer opinions
Even when login verification emails are shown as delivered in logs, various factors can prevent recipients from actually receiving them. These factors span the sending server, the receiving server, the content of the email, and recipient-specific configurations. Issues range from greylisting and delayed filtering rules to content triggering spam filters, poor sender reputation, and recipient-side customizations like custom filters or accidental unsubscribes. Checking authentication (SPF, DKIM, DMARC), monitoring IP and domain reputation, reviewing MX records, engaging content, and ensuring proper list management and permissions are critical for ensuring deliverability.
Marketer view
Email marketer from Email Geeks suggests doing an inbox placement test and a deep dive on metrics for the specific mail stream. If the content is different, it might be the issue, so check for insecure elements (HTTP instead of HTTPS) and ensure images are losslessly compressed.
15 Feb 2024 - Email Geeks
Marketer view
Email marketer from Email on Acid advises ensuring your sending IP or domain isn't on any email blocklists, which can cause delivery issues despite logs showing successful sending.
16 Jul 2023 - Email on Acid
5 expert opinions
Experts suggest a multi-faceted approach to address the issue of login verification emails not being received despite logs showing delivery. This involves scrutinizing delivery details from the sending platform (ideally including a three-digit number, peer IP address, and timestamp), examining recipient MX records, proactively testing inbox placement with seedlisting, verifying DNS records to prevent authentication failures, and continuously monitoring sender reputation as a critical factor influencing email placement.
Expert view
Expert from Spam Resource explains that DNS issues can cause authentication failures (SPF, DKIM, DMARC) that might not be immediately obvious but lead to deliverability problems. Suggests carefully reviewing DNS records.
24 Sep 2021 - Spam Resource
Expert view
Expert from Spam Resource discusses Seedlisting to test inbox placement with real accounts before sending. This proactive approach can help identify if emails are landing in spam folders despite showing as delivered.
28 Apr 2023 - Spam Resource
4 technical articles
Documentation from various sources indicates that even if logs show successful delivery of login verification emails, the recipient's mail server and client configurations play a crucial role in whether the email reaches the intended inbox. Aggressive spam filters, incorrect client configurations, filtering to less obvious folders (like junk or quarantine), and invalid DKIM signatures can all lead to delivery failures despite a successful SMTP transaction. A complete delivery process involves policies and configurations beyond the basic SMTP protocol.
Technical article
Documentation from Microsoft explains that Exchange Online Protection can accept a message but still filter it post-delivery, moving it to junk or quarantine. It suggests checking these locations if the logs indicate successful delivery.
1 May 2025 - Microsoft
Technical article
Documentation from RFC Editor (specifically RFC 5321 on Simple Mail Transfer Protocol) explains that successful SMTP transaction doesn't guarantee inbox delivery. Recipient server can accept the message and later discard or filter it. Full delivery involves policies beyond the basic SMTP protocol.
24 Jul 2022 - RFC Editor
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