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Summary

A sudden increase in Gmail hard bounces, such as a reported 93,000 in a single day for one account, is a significant red flag for email senders. Unlike soft bounces which indicate temporary delivery issues, hard bounces signify a permanent failure, often because the recipient email address does not exist or is invalid. While occasional hard bounces are normal, a sudden spike points to a more systemic problem on the sender's side, rather than a widespread issue with Gmail itself. This could involve recent changes to list acquisition, poor data hygiene, or misconfigurations that lead to sending to unengagable or non-existent addresses.

What email marketers say

When sudden anomalies like a spike in Gmail hard bounces occur, email marketers often turn to community forums and peer discussions to gauge if the issue is widespread or isolated. While some marketers reported not seeing similar widespread issues, indicating the problem might be localized to specific sending practices or accounts, others confirmed experiencing ongoing hard bounce challenges. This varied experience underscores the importance of examining individual sending infrastructure and list hygiene, even when industry-wide issues are suspected. Marketers often focus on identifying specific bounce responses, such as 550 errors, and considering how their Email Service Provider's (ESP) global suppression policies might be affecting their bounce rates.

Marketer view

Marketer from Email Geeks reports they did not observe similar issues to a sudden spike in Gmail hard bounces since 17 hours prior to the discussion. This suggests the issue might not have been widespread across all senders or could have been a transient anomaly. Their data indicated normal sending conditions.

16 Dec 2020 - Email Geeks

Marketer view

Marketer from Email Geeks indicates they had not seen anything like the reported spike in the past few days. They confirmed that their Gmail hard bounce rates appeared normal for that specific day. This provides further evidence that the issue might have been isolated to a particular sending setup or account.

16 Dec 2020 - Email Geeks

What the experts say

Email deliverability experts agree that hard bounces are definitive indicators of an invalid recipient address, signaling a permanent failure. A sudden surge in hard bounces often points to systemic issues, such as problems with list acquisition, outdated data, or even a misconfigured sending system, rather than a temporary anomaly at the receiving end like Gmail. Experts consistently advise immediate removal of such addresses to protect sender reputation. Ignoring high hard bounce rates can lead to severe consequences, including IP and domain blocklisting (blacklisting), reduced inbox placement, and overall poor email deliverability.

Expert view

Expert from SpamResource states that consistently sending to invalid addresses is a primary indicator that a sender is not effectively maintaining their email list. This practice signals to mailbox providers that the sender lacks proper hygiene, which can severely degrade their sender reputation and lead to reduced inbox placement.

22 Mar 2023 - SpamResource

Expert view

Expert from Word to the Wise explains that a hard bounce explicitly means the recipient mail server responded definitively with a "no, this user does not exist" message. This clear signal indicates a permanent failure, making further attempts to send to that address futile and detrimental to reputation.

01 Mar 2023 - Word to the Wise

What the documentation says

Official email deliverability documentation and RFCs consistently define hard bounces as permanent delivery failures. Unlike soft bounces, which are temporary, hard bounces indicate that an email address is invalid, non-existent, or permanently blocked. Therefore, any sudden increase in hard bounces, especially from a major provider like Gmail, usually signifies an issue on the sender's side, such as a compromised list, poor validation, or a policy change by the receiving server that affects what they deem "valid." These permanent failures significantly harm sender reputation and necessitate immediate action to maintain deliverability.

Technical article

Documentation from Mailchimp defines email bounces as occurring when an email cannot be delivered to an email server. It further clarifies that the email server typically provides a reason for the incident, and based on these reasons, bounces are categorized into two types: hard bounces and soft bounces. This classification is fundamental for understanding how to manage email deliverability.

20 Jun 2023 - Mailchimp

Technical article

Documentation from SugarCRM Inc. clarifies that a hard bounce occurs when an email message is permanently rejected. This rejection happens because the recipient email address is either invalid or simply does not exist. This definition underscores the irreversible nature of a hard bounce and the need for senders to remove such addresses.

15 May 2023 - SugarCRM Inc.

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