How does pausing email sending affect IP reputation for warmed vs long-term IPs?

Summary

Pausing email sending negatively impacts IP reputation, especially for newly warmed IPs. While long-term IPs are more resilient, any pause causes some degree of degradation. Maintaining consistent sending volume and frequency is crucial. Gmail is more tolerant of fluctuations than Yahoo and Hotmail/Office 365. It's best to inform ISPs about warmups and, if possible, postpone warmups until after planned pauses. Avoid pausing a warmup that has started. A consistent, though lower, volume is better than spikes followed by pauses.

Key findings

  • IP Cooling Effect: IP reputation begins to degrade immediately upon pausing sending.
  • Warmed IP Vulnerability: Newly warmed IPs are significantly more vulnerable to pauses than long-term IPs.
  • ISPs Differ in Sensitivity: Gmail is more tolerant of volume fluctuations compared to Yahoo and Hotmail/Office 365.
  • Consistency is Paramount: Consistent sending volume and frequency are critical for maintaining a positive IP reputation.

Key considerations

  • Avoid Pauses During Warmup: Avoid pausing sending during IP warm-up, as it can undo the progress made.
  • Prioritize Consistent Volume: Prioritize consistent sending volume over infrequent bursts, even if the volume is lower.
  • Inform ISPs of Warmup: Inform Yahoo and Hotmail/Office 365 about IP warmups to potentially mitigate negative impacts.
  • Delay Warmup if Pause is Planned: If a pause is anticipated, delay the IP warm-up until after the pause to maintain consistency.

What email marketers say
7Marketer opinions

Pausing email sending, especially after warming up an IP, negatively affects IP reputation. While Gmail is more tolerant, Yahoo and Hotmail/Office 365 prioritize consistent volume. Maintaining a consistent sending schedule is essential, particularly for newly warmed IPs, as pauses can undo the progress made.

Key opinions

  • Negative Impact on Reputation: Pausing email sending harms IP reputation, especially for newly warmed IPs.
  • Inconsistency Concerns: Sudden changes in sending volume or frequency negatively affect sender reputation.
  • Gmail Tolerance: Gmail is more tolerant of inconsistent sending compared to Yahoo and Hotmail/Office 365.
  • Newly Warmed IPs: Pauses after warming IPs are particularly damaging, undoing the progress made.

Key considerations

  • Maintain Consistency: Maintain a consistent sending schedule to avoid negatively impacting IP reputation.
  • Inform ISPs: Inform Yahoo and Hotmail/Office 365 about IP warmups to mitigate potential issues.
  • Postpone Warmup: If possible, postpone warming up IPs until after a planned pause to maintain a consistent ramp-up.
  • ISPs sensitivity: Be aware that various ISPs have different sensitivity to inconsistent volume of email sending.
Marketer view

Email marketer from Mailjet explains that sudden changes in sending volume or frequency can negatively affect sender reputation. It's essential to maintain a consistent sending schedule, particularly for warmed IPs.

June 2022 - Mailjet
Marketer view

Email marketer from GlockApps responds that sending frequency and consistency are key factors in sender reputation. Taking a break from sending, especially after a warm-up, can hurt your IP's reputation.

January 2022 - GlockApps
Marketer view

Email marketer from SendGrid shares that consistently sending email is critical for maintaining a good IP reputation. Pausing sending, particularly after a recent warm-up, can undo the progress made.

November 2023 - SendGrid
Marketer view

Email marketer from Email Geeks shares that Gmail is less sensitive to consistent volume than Yahoo or Hotmail/Office 365, which are very volume consistent-centric. He advises informing Yahoo/Hotmail about IP warmups and, if possible, postponing the Hotmail warmup until after the pause.

September 2023 - Email Geeks
Marketer view

Email marketer from StackExchange explains that when warming up IPs you need to remain consistant. If you pause your sending schedules will be affected

May 2022 - StackExchange
Marketer view

Email marketer from Quora responds that when warming IP addresses it is important to send consistently. You should avoid pausing sending as this undoes all the warming up

October 2022 - Quora
Marketer view

Email marketer from Reddit shares that pausing a warmed IP is bad and the IP starts to cool down immediately. But it is more damaging to an IP that is freshly warmed up

January 2025 - Reddit

What the experts say
4Expert opinions

Pausing email sending negatively impacts IP reputation, especially for newly warmed IPs. While long-term IPs are more resilient, any pause causes some degree of 'cooling down.' Maintaining consistent sending volume is crucial; it's better to have a lower, consistent volume than spikes followed by pauses. To avoid complications, it's advised to avoid pausing a warmup that has started.

Key opinions

  • IP Cooling: IPs start to 'cool down' immediately when sending is paused.
  • Warmed IP Vulnerability: Newly warmed IPs are significantly more vulnerable to the negative impacts of pausing sending.
  • Long-Term IP Resilience: Long-term IPs are more resilient to pauses, but still experience some negative impact.
  • Consistency is Key: Maintaining consistent sending volume is crucial for IP reputation.

Key considerations

  • Avoid Pauses During Warmup: Avoid pausing email sending during the IP warmup process.
  • Prioritize Consistency: Prioritize consistent sending volume over infrequent bursts.
  • Lower Volume Option: If necessary, maintain a lower, consistent sending volume rather than stopping completely.
Expert view

Expert from Email Geeks explains that IPs start to cool down immediately during a pause, but the impact is less significant on long-term IPs.

December 2024 - Email Geeks
Expert view

Expert from Email Geeks explains that a 2-week pause is very concerning after only 4 weeks of sending, but not as concerning for an IP used regularly for years. She advises not starting the warmup until after the pause to avoid complications.

February 2023 - Email Geeks
Expert view

Expert from Word to the Wise explains that maintaining consistent sending volume is crucial for IP reputation. Pausing sending can negatively impact reputation, especially for newer IPs. A consistent, though lower, volume is better than spikes followed by pauses.

April 2022 - Word to the Wise
Expert view

Expert from Spam Resource responds that consistency is very important when warming up IPs. You shouldn't be pausing sending to prevent your IP reputation from degrading

December 2022 - Spam Resource

What the documentation says
4Technical articles

Pausing email sending negatively impacts IP reputation, especially for newer IPs that have not established a strong sending history. Consistent sending volume is crucial for maintaining a positive IP reputation, and pausing during IP warm-up is particularly detrimental as it disrupts the establishment of a consistent sending pattern.

Key findings

  • Consistent Sending is Key: Consistently sending emails helps maintain a positive sender reputation.
  • Negative Impact of Pauses: Pauses in sending can negatively impact IP reputation.
  • Detrimental to Warm-up: Pausing sending during IP warm-up disrupts the establishment of a consistent sending pattern.
  • New IPs at Risk: Newer IPs are more vulnerable to reputation damage from sending pauses.

Key considerations

  • Avoid Pauses: Avoid pausing sending, especially during the IP warm-up phase.
  • Maintain Consistency: Maintain a consistent sending volume to protect IP reputation.
  • Ramp-Up Carefully: If starting from a new IP, carefully ramp up sending volume to establish a solid reputation.
Technical article

Documentation from Microsoft responds that consistent sending volume is crucial for maintaining a positive IP reputation with Outlook. A sudden stop in sending can lead to deliverability issues, especially for newly warmed IPs.

January 2022 - Microsoft
Technical article

Documentation from Google explains that consistently sending emails helps maintain a positive sender reputation. Pauses can negatively impact this reputation, especially for newer IPs that haven't built a strong history.

December 2024 - Google
Technical article

Documentation from Amazon AWS states that it is important to be consistent when warming IPs. If you stop sending, your IP reputation may degrade

February 2023 - Amazon AWS
Technical article

Documentation from SparkPost shares that pausing sending during IP warm-up is detrimental. It disrupts the establishment of a consistent sending pattern and can lead to deliverability problems.

February 2025 - SparkPost