Why are my emails delayed in Gmail even with a good reputation and proper authentication?

Email marketer from Email Geeks suggests that Gmail holding onto a message after the 2xx response could indicate that the filter found something to be skeptical of, so it’s being processed with greater analysis.

Email marketer from Reddit shares that your IP address might be on a blocklist despite a good sending reputation. This can happen if the IP was previously used for spamming activities.

Email marketer from Email Marketing Forum responds that if using a shared IP address, the actions of other senders on the same IP can affect your deliverability and cause delays, even if your own sending practices are good.

Email marketer from Email Geeks shares an experience where transactional emails were delayed when a marketing campaign was being sent from the same domain and IP, suggesting Google might be lumping them together and doing additional checks.

Email marketer from Reddit answers that using URL shorteners (like bit.ly) in your emails can sometimes cause delays as they are often associated with spam or phishing attempts.

Email marketer from Neil Patel's Blog explains that even with a good reputation, emails can be delayed due to content triggering spam filters, such as using excessive exclamation points or spammy words.

Email marketer from StackExchange suggests that the receiving server might be running anti-virus or content filtering software, which can add to the processing time and delay delivery.

Email marketer from Email Geeks has noticed Gmail delays (2XX > delay appearing) on a domain by domain basis, but often if we test sending on different/lower volume MTA (HELO) the delay disappears. Suggesting it could be something super mundane like different HELO's getting processed in different queues, and those queues get backlogged for a few days.

Email marketer from Mailjet Blog responds that high email volume sent within a short period can cause delays as Gmail might throttle the incoming connections to prevent abuse.

Email marketer from Litmus Blog responds that inconsistent sending practices (sudden spikes in volume or changes in sending patterns) can trigger spam filters and cause delays, even with proper authentication.

Email marketer from EmailonAcid responds that poor list hygiene (sending to inactive or invalid email addresses) can damage your sender reputation over time, leading to deliverability problems and potential delays.

Email marketer from SendGrid Blog shares that delays could be caused by greylisting, a technique used by some mail servers to temporarily defer emails from unknown senders to combat spam.

Expert from Email Geeks explains ESPs queue emails for each recipient MX. If the queue is full of marketing mail, transactional mail might have to wait.

Expert from SpamResource explains that even with good sender reputation and proper authentication, content within the email itself can cause delays if it triggers spam filters. Things like suspicious links or certain keywords may trigger additional scrutiny.

Expert from Email Geeks mentions thorough research is needed to determine the nature of the issue to know if it really is a unique situation, and getting it wrong will prevent fixing it.

Expert from Email Geeks suggests that the Received headers of a delayed email will show where the delay occurred during delivery and might give an idea of what's going on.

Expert from Email Geeks explains that even a minute of delay can mess with your user experience for transactional stuff like email verification and password resets.

Experts from Email Geeks recommend separating bulk/lower urgency and transactional/higher urgency streams, with some platforms having different priority settings for sending messages.

Expert from Word to the Wise shares that even with a solid reputation and authentication, infrastructure and network configurations can contribute to Gmail delays. Issues include incorrect PTR records or slow reverse DNS lookups can cause delays as Gmail validates sending servers.

Expert from Email Geeks says it is rare but possible, that Gmail thinks some messages need additional spam filter checks and that the process for that isn't as fast as they would like.

Documentation from Spamhaus explains that if your sending IP or domain is listed on a Spamhaus blocklist, emails may be delayed or rejected, even if you have a good reputation elsewhere.

Documentation from RFC 5321 explains that temporary failures (4xx SMTP codes) can cause delays as the sending server will attempt to resend the email after a certain period.

Documentation from Gmail Postmaster Tools explains that it provides metrics that can help identify the cause of email delivery issues like delays by examining spam rate, IP reputation, and authentication status.

Documentation from Google Workspace Admin Help explains that delays can occur if Gmail is experiencing high traffic or outages. Check the Google Workspace Status Dashboard to see if there are any known issues.

Documentation from DKIM.org explains that improperly configured DKIM records can cause delays as recipient servers might need to perform additional checks or temporarily reject emails to verify the sender's authenticity.

Documentation from MXToolbox explains that DNS propagation issues can lead to delays in email delivery as mail servers might not be able to resolve the recipient's domain correctly.