How to troubleshoot significant email delivery delays to Gmail?
Summary
What email marketers say9Marketer opinions
Email marketer from Reddit suggests checking the email content for spam triggers. Excessive use of certain words, large images without alt text, and URL shorteners can sometimes cause delays or deferrals by Gmail.
Marketer from Email Geeks explains that the delay between sending and receiving MTAs doesn't explain why the delay is happening. It could be the sending MTA only attempted delivery at that time, retried with deferrals, or a wrong timestamp.
Email marketer from Litmus shares that Gmail's image caching can sometimes cause delays in email rendering. Ensure that images are properly optimized and hosted on reliable servers to minimize these delays.
Marketer from Email Geeks shares if the ESP reports a soft deferral, that's the reason for the delay. The ESP attempts delivery, and Google requests a retry later. The reason should be in the SMTP error logs.
Email marketer from Email Marketing Forum says that if you've recently started using a new IP address, Gmail may initially delay or defer your emails as part of its anti-spam measures. Gradually increasing sending volume can help establish a positive reputation.
Email marketer from Mailjet Blog shares that regularly monitoring key deliverability metrics like bounce rates, complaint rates, and engagement rates can help identify and address delivery issues before they significantly impact Gmail delivery.
Email marketer from Neil Patel Blog shares that factors affecting email deliverability include sender reputation, email authentication, engagement, and content. Improving these can reduce delays and improve inbox placement.
Email marketer from EmailOctopus Blog shares that to improve sender reputation, consistently send valuable content, clean your email list regularly to remove unengaged subscribers, and authenticate your emails with SPF, DKIM, and DMARC.
Email marketer from ActiveCampaign recommends segmenting your email list based on engagement. Sending to highly engaged segments can improve your sender reputation and reduce delivery delays to Gmail.
What the experts say8Expert opinions
Expert from Email Geeks explains that soft bounces from Gmail contain information about the problem. Provides an example of a soft bounce message.
Expert from Email Geeks shares that the ESP should be able to tell from their log timestamps when they injected the mail and when Google accepted it. The time difference indicates the delay and could be due to queue issues, soft bounces, temporary blocks, or rate limits.
Expert from Email Geeks recommends reading the headers to help diagnose delivery delays and narrow down which server held onto the mail.
Expert from Word to the Wise explains that reviewing the actual SMTP conversation with Gmail can be helpful. Check for any specific error messages or reasons provided by Gmail during the connection that might indicate the cause of the delays.
Expert from Spamresource.com explains that greylisting, a technique used by receiving mail servers to reduce spam, can cause temporary delivery delays. If Gmail is using greylisting, legitimate emails might be deferred for a short period before being accepted.
Expert from Email Geeks says the ESP logs on their MTA will have information about delays, they may just not expose it. The ESP injected the email but the MBP accepted the email hours later indicating that the ESP had the mail in queue for hours.
Expert from Email Geeks warns that Gmail delaying is a sign of reputational problems. It's advisable to pause sending for 24 hours and then resume slowly with the best data.
Expert from Email Geeks states that changing templates is fraught with pain at Gmail.
What the documentation says3Technical articles
Documentation from Postmark explains that reviewing SMTP error codes can provide insight into why emails are delayed. Common issues include temporary server errors (4xx codes) which indicate deferrals, and authentication problems.
Documentation from Google Workspace Admin Help explains that to troubleshoot email delivery issues, check the MX records are set up correctly, that the domain is properly authenticated with SPF, DKIM, and DMARC, and that your sending IP isn't on any blacklists.
Documentation from RFC 5321 explains that SMTP deferrals (temporary failures) are indicated by 4xx series SMTP error codes. These can be due to temporary server unavailability, greylisting, or resource limitations at the receiving server.