Why are transactional emails with passing SPF, DKIM, and DMARC landing in spam?

Email marketer from Litmus shares that low engagement rates (opens, clicks) can negatively impact deliverability. If subscribers are not interacting with transactional emails, mailbox providers may start filtering them as spam.

Email marketer from Neil Patel explains that even with proper authentication, a poor sender reputation can cause emails to land in spam. Reputation is built over time based on subscriber engagement, spam complaints, and bounce rates.

Email marketer from Reddit explains that even with proper authentication, if the sending IP address is on a blocklist, emails will likely land in spam. IP reputation is influenced by the sending history of all users sharing the same IP.

Email marketer from GMass responds that sudden spikes in sending volume can trigger spam filters. Maintaining a consistent sending volume helps establish a predictable sending pattern and improves deliverability.

Email marketer from Quora shares that using a shared IP address can impact deliverability, as the sender's reputation is influenced by the sending practices of other users sharing the same IP. A dedicated IP address gives more control over sender reputation.

Email marketer from Stackoverflow responds that using a 'no-reply' email address can negatively impact deliverability as it discourages engagement and prevents feedback loops. Mailbox providers may view this as a sign of less reputable sending practices.

Email marketer from Mailjet shares that spam filters analyze email content for suspicious keywords, excessive use of capitalization or exclamation points, and poor HTML coding. Transactional emails with content that resembles spam can be filtered despite authentication.

Email marketer from Sendgrid explains that new IP addresses need to be 'warmed up' gradually by sending small volumes of emails and slowly increasing the sending rate. Sending large volumes of emails from a new IP can trigger spam filters, even with proper authentication.

Email marketer from Email on Acid explains the importance of maintaining a clean email list by removing inactive subscribers and invalid email addresses. Sending emails to non-existent addresses can increase bounce rates and negatively impact sender reputation.

Expert from Spam Resource answers that if you've recently increased your sending volume, it's possible that filters are reacting to this change, even if you have proper authentication in place. Sudden increases in volume can be seen as a sign of spam.

Expert from Email Geeks explains if emails are landing in spam despite passing authentication, the issue is likely with content or audience. If it is testing content it is likely a content issue. She also suggests ensuring the rDNS is correctly setup and not a random IP in AWS space and suggests using aboutmy.email to check.

Expert from Email Geeks recommends using a subdomain for dev testing (e.g., devs.mydomain.co) to prevent mistakenly damaging the main domain's reputation.

Expert from Word to the Wise explains that engagement is a critical factor. Even with passing authentication, low open rates, click-through rates, and high deletion rates can signal to mailbox providers that recipients don't want the emails, leading to spam placement.

Expert from Email Geeks shares an experience where automated dev testing generated more receipts than actual customers, with those emails going to a corporate Gmail account. This resulted in Gmail seeing less than half of the messages being interacted with.

Expert from Word to the Wise explains that infrastructure issues, such as incorrect rDNS records, can impact deliverability even when authentication passes. Proper infrastructure setup is essential for establishing trust with mailbox providers.

Documentation from RFC 7489 (DMARC standard) explains that a DMARC policy of 'none' only monitors authentication results and does not instruct receiving mail servers to reject or quarantine messages that fail authentication. A stricter policy of 'quarantine' or 'reject' can improve deliverability but requires careful monitoring.

Documentation from SparkPost shares the value of setting up feedback loops (FBLs) with mailbox providers to receive notifications when subscribers mark emails as spam. This allows senders to identify and remove problematic subscribers from their lists.

Documentation from DKIM.org shares that using an appropriate key length for DKIM signatures is crucial. Shorter key lengths may be considered less secure and can impact deliverability. They recommend using at least a 1024-bit key.

Documentation from Microsoft explains that their SmartScreen filter uses machine learning to identify and filter spam. They advise senders to follow best practices for bulk email, including list hygiene, unsubscribe options, and content quality, to avoid being flagged as spam.

Documentation from Google Postmaster Tools explains that Gmail's spam filters consider various factors beyond authentication, including user reports, email content, and sending patterns. Even with SPF, DKIM, and DMARC, emails can be marked as spam if they trigger these filters.