What causes a sudden increase in email bounce rates after switching to a new email platform?

8 Marketer opinions 3 Expert opinions 4 Technical articles 2 Resources

Summary

A sudden increase in email bounce rates after switching to a new email platform is a multifaceted issue stemming from technical configuration, list hygiene, and reputation factors. Key contributors include the lack of established sender reputation for new IPs and domains, often compounded by failing to implement a proper IP warm-up strategy. Technical setup issues such as incorrect or missing email authentication (SPF, DKIM, DMARC) and DNS records further exacerbate the problem. List quality plays a crucial role, with uncleaned lists containing invalid addresses and a history of suppressed unsubscribes from a previous platform leading to increased bounces. Furthermore, poor list engagement, changes in sending frequency, shared IP reputation, and the presence of 'user unknown' bounces, or being on a blocklist can all significantly impact deliverability. New platforms can also expose underlying list quality issues due to stricter bounce handling or different suppression mechanisms.

Key findings

New IP Reputation: New platforms lack established IP and domain reputation, resulting in higher initial bounce rates.
Authentication Issues: Incorrect or missing SPF, DKIM, and DMARC settings and incorrect DNS records cause emails to be rejected by ISPs.
Poor List Hygiene: Transferring uncleaned email lists with invalid, unsubscribed, or unengaged addresses leads to increased bounces.
Lack of Warm-up: Failing to warm up new IP addresses can trigger spam filters and increase bounce rates.
Shared IP Reputation: On shared IPs, the sending habits of other users affect your email deliverability.
Sending Volume Changes: Drastic changes in sending frequency after migration can negatively impact sender reputation.
Blocklisting: Being on a blocklist will directly increase email bounce rates.
List Quality Revelation: New platforms might expose underlying list quality issues due to stricter bounce handling.
User Unknown Bounces: Likely the presense of invalid email addresses.

Key considerations

IP Warm-up Strategy: Implement a gradual IP warm-up plan to build a positive sender reputation with ISPs.
Email Authentication: Thoroughly verify and configure SPF, DKIM, and DMARC settings, and DNS records correctly.
List Hygiene Practices: Clean your email list regularly to remove invalid, unsubscribed, and unengaged addresses.
Monitor Sending Volume: Gradually increase sending volume after migrating to a new platform to avoid triggering spam filters.
Monitor Reputation: Continuously monitor your IP and domain reputation and engagement to identify and resolve any deliverability issues promptly.
Compliance and Permissions: Ensure the email list is compliant with all regulations and use permission-based email marketing.
Review Bounce Handling: Understand how the new platform handles bounces and suppression and adapt your strategy accordingly.
Address Validation: Confirm and remove invalid user addresses from the email list.

What email marketers say
8Marketer opinions

A sudden increase in email bounce rates after switching to a new email platform can be attributed to several factors. These include neglecting to warm up the new IP address, resulting in a lack of established sender reputation with ISPs. Poor list hygiene, where the old platform may have suppressed bad addresses but the new one doesn't, exposes invalid emails. Incorrect or missing email authentication settings (SPF, DKIM, DMARC) can lead to rejections by ISPs. Additionally, sharing an IP address means the reputation of other senders can impact deliverability. Drastic changes in sending frequency can also negatively affect reputation. Finally, ensuring a compliant, permission-based email list and correct DNS records is crucial for avoiding high bounce rates.

Key opinions

IP Warm-up: New IP addresses require a warm-up period to establish a positive sender reputation with ISPs.
List Hygiene: Transferring an uncleaned email list to a new platform can expose invalid addresses and increase bounces.
Authentication: Incorrect or missing SPF, DKIM, and DMARC settings can cause ISPs to reject emails.
Shared IP: The reputation of other senders on a shared IP address can impact your deliverability.
Sending Frequency: Drastic changes in sending frequency can negatively affect sender reputation.
List Compliance: A non-compliant, non-permission based list can cause high bounce rates on new platforms.
DNS Records: Incorrect DNS records can cause authentication issues and bounce rates.

Key considerations

Warm-up Strategy: Implement a gradual IP warm-up strategy to build a positive sender reputation.
List Cleaning: Thoroughly clean your email list to remove invalid and unengaged addresses before migrating to the new platform.
Authentication Setup: Verify and configure SPF, DKIM, and DMARC settings correctly on the new platform.
Monitor Reputation: Monitor your IP and domain reputation to identify and address any deliverability issues promptly.
Sending Volume: Avoid drastic changes in sending volume after switching platforms; gradually increase volume.
Compliance: Use compliant email lists where recipients have recently opted-in.
DNS Records: Verify that your DNS records for email authentication are correct.

Marketer view

Email marketer from ActiveCampaign explains that sender reputation is a key factor for deliverability. Moving to a new platform means starting over with reputation. Engage in IP warming practices and email authentication to build a good reputation.

March 2024 - ActiveCampaign

Marketer view

Email marketer from MailerQ.com explains that a sudden increase in bounce rates after switching platforms can be due to not properly warming up the new IP address. Reputation needs to be built with ISPs to ensure emails are delivered.

September 2021 - MailerQ.com

Marketer view

Email marketer from GlockApps answers that incorrect DNS records after the platform change will cause authentication issues and bounce rates. Make sure the DNS records are correct.

June 2023 - GlockApps

Marketer view

Email marketer from SendPulse Blog answers that incorrect or missing email authentication (SPF, DKIM, DMARC) settings on the new platform can cause a surge in bounces. ISPs use these to verify senders; improper setup leads to rejections.

July 2021 - SendPulse Blog

Marketer view

Email marketer from Automizy Blog shares that poor list hygiene is a major cause. The old platform might have automatically suppressed bad addresses; transferring an uncleaned list to the new platform exposes these invalid emails, leading to bounces.

June 2022 - Automizy Blog

Marketer view

Email marketer from Reddit user shares that if you're on a shared IP address, the reputation of other senders can affect your deliverability. A new platform might have a different IP pool with varying reputations, leading to increased bounces.

July 2023 - Reddit

Marketer view

Email marketer from GMass shares that not having a compliant and permission-based email list can cause high bounce rates with new platforms. Ensure all recipients have opted-in recently and are expecting your emails.

March 2022 - GMass

Marketer view

Email marketer from StackExchange user answers that changing sending frequency too drastically after switching platforms can negatively impact reputation, causing bounces. ISPs are wary of sudden volume changes.

January 2023 - StackExchange

What the experts say
3Expert opinions

Experts attribute the sudden increase in email bounce rates after switching platforms to a few key reasons. A likely cause is the presence of 'user unknown' bounces, suggesting invalid users in the email list; for O365 accounts, submitting a support request to Microsoft might help. Additionally, if the previous platform suppressed unsubscribed and bouncing addresses, failing to clean the list before migrating exposes these addresses, leading to higher bounce rates. Furthermore, the new platform's potentially stricter bounce handling or different suppression mechanisms can reveal underlying list quality problems, even if they existed before the switch. Beyond list quality, technical setup issues also contribute to increased bounce rates during platform migration.

Key opinions

User Unknown Bounces: Increased 'user unknown' bounces often indicate invalid email addresses.
Suppressed Addresses: Previous platform's suppression of unsubscribed or bouncing addresses, if not reflected in the migrated list, leads to higher bounces.
List Quality Issues: A new platform can expose underlying list quality problems due to stricter bounce handling.
Technical Setup: Technical setup during migration can affect bounce rates.

Key considerations

Verify Invalid Users: Confirm and remove invalid user addresses from the email list.
List Cleaning: Thoroughly clean the email list to remove unsubscribed and bouncing addresses before migrating.
Platform Differences: Understand how the new platform handles bounces and suppression compared to the old one.
Technical Review: Ensure all technical aspects of the migration are correctly configured to avoid unexpected bounce rates.

Expert view

Expert from Email Geeks explains that if the previous platform suppressed unsubscribed and bouncing addresses, and the list wasn’t cleaned before the new platform, high bounce rates could occur.

February 2022 - Email Geeks

Expert view

Expert from Word to the Wise explains that a sudden increase in bounce rates after switching platforms often reveals underlying list quality issues. The new platform may be more strict with bounces or may not suppress bounces as quickly/effectively as the old platform. Therefore, what appears to be a new problem is often just an old one being exposed. In addition to list quality, technical setup can also affect bounce rates after a platform migration.

November 2024 - Word to the Wise

Expert view

Expert from Email Geeks suggests that the bounces are likely user unknown bounces and recommends confirming if they are invalid users. For O365 accounts, the company or domain owner could submit a support request to Microsoft.

July 2024 - Email Geeks

What the documentation says
4Technical articles

Documentation suggests several technical reasons for increased bounce rates after switching email platforms. A primary factor is the lack of established reputation for the new platform's IP address and sending domain; sending high volumes immediately triggers spam filters. Specific SMTP error codes, like 550 5.1.1, point to recipient mailbox issues, indicating more invalid addresses being attempted. Poor list engagement also contributes, as unengaged recipients are more likely to bounce or be marked as spam, especially when sender reputation is unproven. Lastly, being on a blocklist directly increases bounce rates, necessitating regular checks and removal requests.

Key findings

New IP Reputation: New platforms lack established IP and domain reputation, increasing bounce rates.
SMTP Errors: Increased SMTP error codes (e.g., 550 5.1.1) indicate recipient mailbox problems and invalid addresses.
List Engagement: Poor list engagement contributes to higher bounce rates, especially on new platforms.
Blocklisting: Being on a blocklist directly increases email bounce rates.

Key considerations

IP Warm-up: Implement a gradual IP warm-up to establish a positive sender reputation with ISPs.
Address Validation: Regularly validate email addresses to minimize bounces caused by invalid recipients.
Engagement Monitoring: Monitor and improve list engagement to reduce bounces and spam complaints.
Blocklist Checks: Regularly check if your IP or domain is on a blocklist and request removal if necessary.

Technical article

Documentation from Amazon Web Services explains that a new platform's IP address and sending domain likely have no established reputation. Sending a high volume of emails immediately can trigger spam filters and increase bounce rates. Gradual warm-up is essential.

March 2021 - Amazon Web Services

Technical article

Documentation from MessageBird details that poor list engagement can cause increase in bounces. It explains that recipients who don't engage are more likely to result in bounces or being marked as spam, especially on a new platform where sender reputation is unproven.

July 2024 - MessageBird

Technical article

Documentation from Microsoft explains that if your IP or domain is on a blocklist, it will increase bounce rates. Use tools to check if you are blocklisted and request removal if necessary.

March 2024 - Microsoft

Technical article

Documentation from RFC-Editor.org details that specific SMTP error codes (like 550 5.1.1) indicate recipient mailbox issues. A sudden increase in these errors means more invalid addresses are being attempted, compared to the old platform.

March 2021 - RFC-Editor.org