How strict are sending caps during email IP warming?

Summary

IP warming guidance is often considered imprecise, but adherence to a gradual and consistent sending schedule is crucial. While minor variances in sending volumes might be acceptable depending on list quality and targeting, sudden spikes should be avoided. Experts recommend starting with low volumes, slowly increasing based on engagement, and ensuring a clean IP history. A common misconception is warming exclusively with highly engaged users; a balanced approach is better.

Key findings

  • Guidance Imprecision: Warming guidance often relies on best guesses and may not be rigidly enforced.
  • Gradual Volume Increase: Starting with low volumes and gradually increasing them is essential.
  • Importance of Consistency: Maintaining a regular sending frequency is key for building a positive reputation.
  • List Quality Impact: The acceptability of exceeding sending caps depends on list quality and targeting.
  • Clean IP Necessity: A clean IP history is vital for successful IP warming and deliverability.
  • Balanced Engagement Mix: Sending to a mix of users, not just the most engaged, is recommended.

Key considerations

  • List Segmentation: Consider segmenting your list and targeting users appropriately during warming.
  • IP Health Verification: Verify your IP's reputation before initiating email campaigns.
  • Throttling Implementation: Implement throttling mechanisms to manage sending volumes.
  • Engagement Monitoring: Closely monitor engagement metrics and adjust sending practices accordingly.
  • Ramp-Up Planning: Develop a carefully planned ramp-up strategy to avoid sudden spikes.

What email marketers say
9Marketer opinions

During IP warming, adhering to sending caps is important but not always rigidly enforced. While exceeding limits slightly might be acceptable depending on list quality and targeting, consistency is key. Experts recommend starting with low sending volumes and gradually increasing them to avoid damaging sender reputation. Factors like list quality and the use of throttling mechanisms can influence the impact of exceeding these limits.

Key opinions

  • Sending Cap Flexibility: Exceeding sending caps by a small margin might be acceptable based on list quality and targeting.
  • Importance of Consistency: Maintaining a regular sending frequency and volume is crucial for building a positive sender reputation.
  • Gradual Volume Increase: Experts recommend starting with low sending volumes and gradually increasing them over time.
  • Potential Damage: Sending too many emails too quickly during IP warming can damage sender reputation, leading to emails being marked as spam.

Key considerations

  • List Quality: Ensure a high-quality email list with engaged subscribers and low bounce rates.
  • Throttling: Implement throttling mechanisms to manage sending volume and prevent exceeding limits significantly.
  • Deliverability Monitoring: Closely monitor deliverability rates and adjust sending practices accordingly.
  • Erratic Patterns: Avoid creating erratic sending patterns that raise red flags.
Marketer view

Email marketer from SendGrid states that consistency is key during IP warming. Maintain a regular sending frequency and volume to build a positive sending reputation with ISPs. Erratic sending patterns can raise red flags.

August 2021 - SendGrid
Marketer view

Email marketer from Mailjet shares that it's best to start with small, consistent sending volumes during IP warming, gradually increasing the amount as your reputation grows. Sending too much too soon can hurt your deliverability.

December 2023 - Mailjet
Marketer view

Email marketer from Reddit user shares that exceeding the daily sending limit by a small amount (e.g., 10-20%) during IP warming is generally acceptable, but it's best to stay within the recommended range. Monitor your deliverability closely and adjust accordingly.

July 2021 - Reddit
Marketer view

Email marketer from Email Geeks shares that exceeding warming sending caps slightly should be ok, as the volumes are guides. The ability to push these guides depends on list quality and targeting. Adding throttling can help if you go over.

May 2021 - Email Geeks
Marketer view

Email marketer from Email Marketing Forum shared the strategy of adding throttling when you go over your allocated limit.

October 2024 - Email Marketing Forum
Marketer view

Email marketer from Gmass, recommends starting with a low sending volume (e.g., 50-100 emails per day) and gradually increasing it by 10-20% each day or week during IP warming. The key is to avoid sudden spikes in volume.

January 2024 - Gmass
Marketer view

Email marketer from Constant Contact warns that sending too many emails too quickly during IP warming can damage your sender reputation. This can lead to your emails being marked as spam and harm your deliverability.

March 2023 - Constant Contact
Marketer view

Email marketer from Email Provider Review suggests generally speaking, warming guidance is all hand-wavy and involves a lot of best guessing. Minor variances are not likely to tank your best efforts.

March 2025 - Email Provider Review
Marketer view

Email marketer from ActiveCampaign highlights that list quality is crucial during IP warming. Sending to engaged subscribers with a low bounce rate will help build a positive sender reputation.

August 2021 - ActiveCampaign

What the experts say
3Expert opinions

IP warming guidance is often considered imprecise, and slight variations in sending volumes may not be detrimental. A common misconception is that warming should begin with only highly engaged users, which can appear suspicious to providers. It's crucial to ensure a clean IP history before warming to avoid deliverability issues.

Key opinions

  • Warming Guidance Imprecision: Warming guidance often relies on best guesses rather than strict rules.
  • Misconception of Engaged Users: Starting exclusively with engaged users can raise red flags.
  • Importance of Clean IP: A clean IP history is vital for successful IP warming and deliverability.

Key considerations

  • IP Health Verification: Verify the IP's reputation before initiating any email campaigns.
  • Balanced Engagement Mix: Send emails to a mix of users, not just the most engaged.
  • Acceptable Variance: Minor differences in sending volumes are unlikely to have significant negative impacts.
Expert view

Expert from Email Geeks explains that warming guidance is generally hand-wavy and involves a lot of best guessing, so minor variances in sending volumes are not likely to tank your best efforts.

May 2023 - Email Geeks
Expert view

Expert from Spam Resource shares that ensuring a clean IP history is vital before commencing IP warming. A tainted IP may hinder the warming process and impact deliverability rates. Therefore, it's essential to verify the IP's reputation and undertake necessary cleansing measures before initiating any email campaigns.

January 2022 - Spam Resource
Expert view

Expert from Word to the Wise explains that it's a common misbelief that you should start warming by sending email to your most engaged users only. In some cases this has resulted in providers seeing this as odd since all the email is opened. They suggest creating a mix of send to your whole file, and not just to the most engaged.

March 2024 - Word to the Wise

What the documentation says
3Technical articles

All three documentation sources emphasize the critical importance of a gradual and consistent sending schedule during IP warming. Sudden spikes in volume are to be avoided. Instead, a slow and planned increase in email volume is required to build a positive sending reputation with ISPs. The exact numbers for the ramp-up process are dependent on the overall size of your email sending but should always be gradual and planned.

Key findings

  • Gradual Ramp-Up: A gradual ramp-up of sending volume is essential during IP warming.
  • Avoid Volume Spikes: Sudden and large increases in sending volume should be avoided.
  • Consistency is Key: A consistent sending schedule contributes to building a positive reputation.

Key considerations

  • Plan the Ramp-Up: Develop a carefully planned ramp-up strategy based on expected sending size.
  • Monitor Engagement: Base volume increases on positive engagement metrics.
  • Be Patient: The warming process takes time, so avoid rushing the volume increase.
Technical article

Documentation from MailChannels stresses that sudden jumps in sending volume are a common cause of deliverability problems for new IPs. Their documentation advocates a carefully planned ramp-up, starting with very low volumes and gradually increasing sending based on positive engagement.

December 2021 - MailChannels
Technical article

Documentation from SparkPost emphasizes the importance of a gradual and consistent sending schedule during IP warming. Avoid sudden spikes in volume, and slowly increase the number of emails sent each day or week. The exact numbers depend on the overall size of your sending but must be gradual.

January 2024 - SparkPost
Technical article

Documentation from Amazon Web Services states that it's essential to gradually ramp up your sending volume during IP warming. Avoid sending large amounts of email all at once. Instead, start with a small number of emails and gradually increase the volume over time.

December 2021 - Amazon Web Services