Should I be concerned about identical traffic patterns when migrating to a new SMTP provider?

Summary

Migrating to a new SMTP provider requires careful planning to avoid negatively impacting email deliverability. A key concern is maintaining a good sender reputation. Experts and documentation consistently advise a gradual IP warm-up process where sending volumes are slowly increased. Monitoring sender reputation, bounce rates, inbox placement, and blocklists are critical. Maintaining list hygiene by removing unengaged addresses and avoiding abrupt changes in sending habits are also essential to prevent triggering spam filters. Some mailbox providers may benefit from dedicated IPs. Initial identical traffic patterns during the warm-up phase are generally expected but should evolve as traffic increases. A high number of traffic sources is more concerning than a few. Deviation from recognized traffic patterns will impact reputation.

Key findings

  • IP Warm-up is Critical: Gradual IP warm-up is essential to avoid being flagged as spam by ISPs; sudden large volumes from a new IP raise red flags.
  • Monitor Sending Reputation: Closely monitor sender reputation, bounce rates, inbox placement, and blocklists during and after migration.
  • List Hygiene Matters: Maintaining list hygiene by removing unengaged addresses is crucial for deliverability.
  • Traffic Sources Impact: The number of traffic sources from a new SMTP impacts the level of concern; many sources raise more concerns.
  • Consistency is Key: Maintaining consistent sending habits, frequency, and content prevents triggering spam filters.
  • Dedicated IPs Can Help: Some mailbox providers benefit from dedicated IPs, especially for clients who can support them.
  • Warm-up Traffic: Seeing identical traffic patterns during the warm-up period is normal but the traffic needs to increase.

Key considerations

  • Implement Gradual Warm-up: Slowly increase sending volume and engagement rates to build trust with ISPs during IP warm-up.
  • Monitor Key Metrics: Continuously monitor key deliverability metrics like inbox placement rate, spam complaints, and bounce rates to identify issues quickly.
  • Clean Your Lists Regularly: Regularly clean your mailing lists to remove unengaged addresses and spam traps.
  • Evaluate Dedicated IPs: Assess the need for dedicated IPs based on client needs and mailbox provider recommendations.
  • Maintain Consistent Sending Habits: Avoid abrupt changes in sending volume, frequency, and content during migration.
  • Adhere to Standards: Conform with SMTP standards to guarantee reliable traffic.
  • Plan for Initial Warmup: Plan for a short period where sending traffic patterns are identical while the SMTP is initially being warmed.

What email marketers say
9Marketer opinions

Migrating to a new SMTP provider requires careful planning to avoid negative impacts on email deliverability. Experts consistently advise a gradual IP warm-up strategy, which involves slowly increasing sending volume to build trust with ISPs. Monitoring sender reputation, bounce rates, and inbox placement are essential for identifying and addressing any issues quickly. Maintaining list hygiene and avoiding sudden changes in sending patterns are also crucial to prevent being flagged as spam and ensure a smooth transition.

Key opinions

  • IP Warm-up: Gradual IP warm-up is crucial to avoid being flagged as spam. Sudden large volumes from a new IP can raise red flags.
  • Reputation Monitoring: Closely monitor sender reputation, bounce rates, and inbox placement during and after migration.
  • Deliverability Dips: Expect potential deliverability dips during the migration process and be prepared to adjust strategies accordingly.
  • Domain Reputation: Domain reputation can be affected by inconsistencies in traffic patterns.

Key considerations

  • Gradual Increase: Gradually increase sending volume and engagement rates to build trust with ISPs.
  • Monitor Metrics: Monitor key deliverability metrics such as inbox placement rate and spam complaints.
  • List Hygiene: Maintain list hygiene to avoid sending to old or unengaged addresses.
  • Blocklist Monitoring: Monitor blocklists during migration.
Marketer view

Email marketer from Campaign Monitor answers that domain reputation can be affected, especially if there are inconsistencies in traffic patterns during an SMTP migration.

November 2024 - Campaign Monitor
Marketer view

Email marketer from Email on Acid mentions keeping track of your email volume. Drastic changes can affect your sender reputation.

April 2023 - Email On Acid
Marketer view

Email marketer from StackOverflow suggests slow IP Warmup is key and also highlights monitoring blocklists during migration.

June 2023 - StackOverflow
Marketer view

Email marketer from Reddit user u/EmailNoob42 suggests that it's common to see deliverability dips during SMTP migrations. He advises to keep a close eye on bounce rates and sender reputation and adjust your strategy accordingly.

March 2023 - Reddit
Marketer view

Email marketer from Litmus states that monitoring key deliverability metrics, such as inbox placement rate and spam complaints, is crucial when transitioning to a new SMTP provider. He explains that this helps identify and address any potential issues quickly.

July 2022 - Litmus
Marketer view

Email marketer from Mailjet shares that you should monitor your sending reputation closely when switching SMTP providers. They explain that any sudden changes in sending patterns can negatively impact deliverability and that you should start slowly.

September 2024 - Mailjet
Marketer view

Email marketer from Neil Patel's Blog explains that it's essential to warm up your new IP address gradually when migrating SMTP providers to avoid being flagged as spam. Sudden large volumes from a new IP can raise red flags.

July 2023 - Neil Patel's Blog
Marketer view

Email marketer from Gmass shares the key is warming up the new IP. Without a gradual increase you will likely be sent straight to spam.

March 2023 - Gmass
Marketer view

Email marketer from SendGrid explains that a slow and steady IP warm-up strategy is crucial when moving to a new SMTP. This means gradually increasing sending volume and monitoring engagement rates to build trust with ISPs.

March 2022 - SendGrid

What the experts say
5Expert opinions

When migrating to a new SMTP provider, identical traffic patterns are a valid concern. Experts suggest that the level of concern depends on the number of sources of the new traffic; more sources are more concerning. Gradual IP warm-up is vital to avoid triggering spam filters due to sudden shifts in traffic. Maintaining good list hygiene by avoiding sending to unengaged addresses is also crucial. While shared IP pools might be sufficient in the future, some mailbox providers still benefit from dedicated IPs. Seeing similar patterns during warmup is considered normal.

Key opinions

  • Traffic Source Count: The number of sources for the new traffic impacts the level of concern; hundreds of sources are more concerning than just a few.
  • IP Warmup Importance: Gradual IP warm-up is crucial for building a sending reputation and avoiding spam filters.
  • List Hygiene: Maintaining list hygiene is crucial during SMTP migrations to avoid deliverability issues.
  • Shared vs. Dedicated IPs: Some mailbox providers may benefit from dedicated IPs, especially for clients who can support them.
  • Warmup Traffic Patterns: Identical traffic patterns during warmup are generally normal.

Key considerations

  • Warm-up Gradually: Ease into the new SMTP with a slow increase in email volume.
  • Maintain List Hygiene: Remove unengaged addresses from your mailing list.
  • Monitor Reputation: Closely monitor your sending reputation with mailbox providers.
  • Consider Dedicated IPs: Evaluate whether dedicated IPs are necessary based on client needs and mailbox provider requirements.
Expert view

Expert from Spam Resource emphasizes a gradual IP warmup when migrating, highlighting that ISPs track traffic patterns closely. They explain that a sudden shift could trigger spam filters, so easing into the new SMTP with a slow increase is vital.

April 2024 - Spam Resource
Expert view

Expert from Word to the Wise explains that maintaining list hygiene is crucial during SMTP migrations. She mentions that sending to old or unengaged addresses on a new SMTP provider could lead to deliverability issues and trigger spam traps, resulting in negative consequences.

December 2022 - Word to the Wise
Expert view

Expert from Email Geeks explains that if the new traffic comes from hundreds of sources it is concerning, but if it comes from 2 sources it is not as concerning. They also state that shared versus dedicated domain is probably not concerning and concludes that the user is on the best path, and he probably shouldn't worry about it.

April 2023 - Email Geeks
Expert view

Expert from Email Geeks shares that while shared pools might be good enough in the future, some mailbox providers (like Microsoft) still benefit from dedicated IPs for clients who can support them.

February 2025 - Email Geeks
Expert view

Expert from Email Geeks shares that seeing identical traffic patterns from old and new domains during SMTP migration is normal with warmup. She explains as long as you're not sending 100 emails over 100 IPs you're fine.

June 2021 - Email Geeks

What the documentation says
5Technical articles

Official documentation emphasizes the importance of consistent sending patterns and gradual increases in email volume when migrating to a new SMTP provider. Avoid sending large bursts of email from a new IP address, as this can negatively impact your reputation and trigger spam filters. Maintaining consistent sending habits, frequency, and content is crucial. Monitor your IP reputation and sending limits closely during the migration process, as deviations from established traffic patterns can affect your reputation with mailbox providers like Gmail and Microsoft.

Key findings

  • Consistent Volume: Consistently increase email volume over time to build a positive reputation.
  • Avoid Bursts: Avoid sending large bursts of email from a new IP address.
  • Consistent Habits: Maintain consistent sending habits, frequency, and content.
  • Pattern Recognition: Mailbox providers observe traffic patterns to determine sender reputation; deviations impact reputation.
  • Reputation and Limits: Keep a close eye on your IP reputation and sending limits during the SMTP migration.

Key considerations

  • Gradual Increase: Gradually increase email volume to warm up new IPs and build reputation.
  • Monitor Reputation: Monitor your sender reputation with mailbox providers throughout the migration process.
  • Maintain Consistency: Maintain consistent sending patterns, frequency, and content during the migration.
  • Adhere to Standards: Adhere to SMTP standards to ensure reliable traffic.
Technical article

Documentation from RFC details standards around SMTP. It provides insight on expected patterns and how deviations could be viewed. While not explicit it does indicate an expectation of consistent and reliable traffic.

September 2021 - RFC 5321
Technical article

Documentation from Microsoft details how they observe and learn traffic patterns to determine reputation. Any deviations from these patterns could impact reputation.

May 2023 - Microsoft
Technical article

Documentation from SparkPost stresses the importance of maintaining consistent sending habits when migrating to a new SMTP. They explain that abrupt changes in sending volume, frequency, or content can trigger spam filters.

August 2023 - SparkPost
Technical article

Documentation from Google Postmaster Tools outlines the importance of consistently increasing email volume over time to build a positive reputation with Gmail. They state to avoid sending large bursts of email from a new IP address.

June 2023 - Google Postmaster Tools
Technical article

Documentation from AWS explains that for AWS SES, you need to keep a close eye on your IP reputation and sending limits during an SMTP migration.

September 2021 - AWS