Summary
During IP warming, both soft bounces and unsubscribe rates are critical signals to Gmail about a sender's list hygiene and engagement practices. High soft bounce rates, often due to full inboxes or outdated addresses, indicate poor list quality and can negatively impact sender reputation. High unsubscribe rates, while preferred over spam complaints, also raise concerns if they point to irrelevant content or a lack of permission. Experts, marketers, and documentation all emphasize the importance of cleaning lists, targeting engaged users, and ensuring permission-based acquisition to maintain a positive sender reputation and achieve successful IP warming. Using reliable engagement data, monitoring key metrics, and promptly addressing any issues are also crucial.
Key findings
- Poor List = Soft Bounces: High soft bounce rates often stem from outdated, inactive, or full inboxes, signaling poor list quality to Gmail.
- Relevance & Permission Matter: High unsubscribe rates suggest a mismatch between content and recipient expectations or a lack of explicit permission to send.
- Unsubs Beat Spam: While high numbers are still an issue, unsubscribes are viewed more favorably by MBPs than spam complaints.
- Engagement is Key: Using clean, permission-based lists with active engagement data is crucial during IP warming to build a positive reputation.
Key considerations
- Clean Your List: Implement robust list hygiene practices, removing inactive, invalid, or unengaged subscribers.
- Gain Explicit Permission: Focus on acquiring subscribers through permission-based methods, ensuring recipients actively opt-in.
- Monitor & React: Closely monitor soft bounce and unsubscribe rates during IP warming, taking prompt action to address any issues.
- Relevance is Key: Continuously improve content relevance and targeting to minimize unsubscribes and maximize engagement.
What email marketers say
13 marketer opinions
During IP warming, both soft bounces and unsubscribe rates significantly impact Gmail sender reputation. High soft bounce rates, often stemming from full inboxes or inactive addresses, signal poor list quality and a lack of email hygiene to Gmail. Elevated unsubscribe rates indicate a disconnect between sender and recipient expectations, potentially due to irrelevant content or unrequested emails. Both metrics can lead to deliverability issues, prompting Gmail to view the sender with caution and potentially filter emails to spam. Cleaning the email list, targeting engaged subscribers, and ensuring permission-based acquisition are crucial strategies to mitigate negative impacts and maintain a positive sender reputation during IP warming.
Key opinions
- Soft Bounces = Poor List Quality: High soft bounce rates during IP warming indicate poor list quality and a lack of email hygiene, signaling to Gmail that the sender isn't practicing good email list management.
- Unsubscribes = Relevance Issues: Elevated unsubscribe rates early in the IP warming process suggest recipients didn't opt-in or the content isn't relevant, leading to lower engagement and potentially harming sender reputation.
- List Scrubbing is Crucial: Cleaning the email list before and during IP warming is essential to avoid high soft bounce and unsubscribe rates, which can lead Gmail to perceive the sender as a spammer.
- Engagement Targeting is Key: Targeting engaged subscribers during IP warming is critical to demonstrate positive engagement to Gmail and maintain a good sender reputation.
Key considerations
- Prioritize List Hygiene: Implement robust list cleaning practices to remove invalid or inactive addresses and reduce soft bounce rates.
- Ensure Permission-Based Acquisition: Focus on acquiring email addresses through permission-based methods to ensure recipients expect and want your emails, minimizing unsubscribe rates.
- Monitor Metrics Closely: Carefully monitor soft bounce and unsubscribe rates during IP warming to identify and address any potential issues promptly.
- Targeted Content Strategies: Focus on building a persona and creating better targeted content to drive down the unsubscribes and improve engagement.
Marketer view
Email marketer from Constant Contact explains that while you are IP Warming you should take care to avoid soft bounces and spam traps to ensure a good Sender Reputation. High unsubscribe rates early on signal that recipients aren't expecting your emails, which can hurt your sender reputation and future deliverability.
19 Jan 2022 - Constant Contact
Marketer view
Email marketer from Email Geeks explains that if unsub-click makes up a high % ratio of uClick it generally indicates “friction” - which speaks to more macro issues of relevance, over-communication, etc.
9 Dec 2022 - Email Geeks
What the experts say
7 expert opinions
Experts agree that soft bounces and unsubscribe rates during IP warming are critical indicators of list health and sender practices. High soft bounce rates, often linked to outdated or unengaged lists, signal poor data quality. Excessive unsubscribes point to issues with list acquisition and relevance. While unsubscribes are preferable to spam complaints, their high volume can still negatively impact sender reputation. Using clean, permission-based lists and regularly assessing engagement data are crucial for successful IP warming.
Key opinions
- Unsubscribes vs. Spam Complaints: Major mailbox providers (MBPs) view unsubscribes more favorably than spam complaints.
- Data Quality Matters: High soft bounces indicate poor data quality, suggesting the need for cleaner lists and better list hygiene.
- List Acquisition is Key: Poor list acquisition practices (e.g., scraping, using old lists) are a primary cause of high soft bounces and unsubscribes during IP warming.
- Engagement Data Reliability: Old engagement data may be unreliable, necessitating reevaluation of segmentation strategies.
Key considerations
- Prioritize Clean Data: Start with a clean, permission-based list to minimize soft bounces and unsubscribes.
- Rethink Segmentation: Re-evaluate segmentation strategies if soft bounces are high, indicating potential issues with data accuracy.
- Focus on Permission: Ensure all subscribers have explicitly opted in to receive emails.
- Monitor Engagement: Regularly assess engagement metrics (opens, clicks) to identify and remove unengaged subscribers.
Expert view
Expert from Email Geeks shares that engagement on a clicked link is better than a spam click and so unsubscribes are more of a positive thing.
12 Jun 2025 - Email Geeks
Expert view
Expert from Email Geeks responds about soft bounces for over quota and indicates that you might not be using the cleanest data to send with. They advise to go back and look at the data you’re using to warm up and rethink the segmentation.
6 Jun 2023 - Email Geeks
What the documentation says
5 technical articles
Email service provider documentation consistently highlights the negative impact of high soft bounce and unsubscribe rates on sender reputation during IP warming. Soft bounces, particularly when persistent, signal poor list hygiene and potential illegitimate sending practices. Elevated unsubscribe rates indicate a mismatch between sender expectations and delivered content, raising concerns about consent and relevance. Both issues can lead to deliverability problems, prompting Gmail and other ISPs to view the sender with caution and potentially throttle or block emails.
Key findings
- Soft Bounces Impact Reputation: High soft bounce rates during IP warming negatively impact sender reputation, indicating issues with list hygiene or sending practices.
- Unsubscribes Signal Mismatch: High unsubscribe rates during IP warming indicate a mismatch between recipient expectations and email content.
- Early Stage Impact: Problems early on will cause ISPs like Gmail that there's a problem with the sender's practices, which can throttle or block emails.
- Sender Authenticity: Mail transfer agents might incorrectly think the IP is not being used by a legitimate sender.
Key considerations
- Maintain List Hygiene: Implement strict list hygiene practices to minimize soft bounces and improve sender reputation.
- Ensure Content Relevance: Ensure content is relevant and targeted to meet recipient expectations and reduce unsubscribe rates.
- Monitor Performance: Closely monitor soft bounce and unsubscribe rates during IP warming to identify and address potential deliverability issues promptly.
- List Validation: Ensure your list are valid.
Technical article
Documentation from Mailchimp explains that during IP warming, high soft bounce rates can indicate that you are sending to invalid or inactive addresses, which can damage your sender reputation. Also, High unsubscribe rates can indicate that recipients are not expecting your emails, which can also damage your sender reputation.
20 Nov 2021 - Mailchimp
Technical article
Documentation from MailerQ Documentation explains that soft bounces can be particularly harmful during IP warming, because they can indicate that your IP is being used by someone who is not a legitimate sender. High unsubscribe rates also tell ISPs that your mail is unwanted.
20 Dec 2022 - MailerQ Documentation
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