Does send time impact IP warmup and reputation when using a new ESP?

Summary

The consensus is that send time is less critical than other factors during IP warming. Experts and documentation alike emphasize gradual volume increases, consistent sending patterns, and focusing on engaged recipients. List quality, authentication (SPF, DKIM, DMARC), and relevant content are highlighted as more impactful on reputation and deliverability than the specific time of day emails are sent. Some suggest considering sending off-peak to improve throughput, and others suggest aligning with when your audience expects to receive email, but overall, the emphasis is on building trust with ISPs through steady, engaged sending habits.

Key findings

  • Volume Graduality: Gradually increasing email volume is crucial for establishing a positive sending reputation.
  • Consistency Wins: Maintaining consistent sending patterns and frequency helps build trust with ISPs.
  • Engagement is Key: Focusing on sending to engaged subscribers boosts sender reputation and deliverability.
  • Authentication Matters: Proper email authentication (SPF, DKIM, DMARC) significantly improves deliverability.
  • Time is Secondary: The specific time of day emails are sent is less critical than other factors.

Key considerations

  • List Segmentation: Segment your email list and target only your most engaged users during the initial warmup.
  • Audience Relevance: Ensure your content is relevant and valuable to your audience to improve engagement.
  • Deliverability Monitoring: Closely monitor deliverability metrics like bounce rates and spam complaints.
  • IP Diversity: If using multiple IPs, warm them up individually to prevent reputation dilution.
  • Off-Peak Sending: Consider staggering send times to avoid peak sending periods and improve throughput.

What email marketers say
12Marketer opinions

When warming up a new IP address, the consensus is that send time is less critical than consistency, engagement, and gradual volume increases. While some suggest aligning with typical subscriber send times, most experts emphasize starting with small volumes to engaged users, gradually increasing over time, and monitoring deliverability metrics. Segmenting lists and ensuring proper authentication are also vital.

Key opinions

  • Send Time Irrelevant: Send time has little impact on reputation calculations as these are rolled into hourly or daily calculations.
  • Consistency Matters: Establishing a consistent sending schedule is essential for IP warming.
  • Gradual Increase: Gradually increasing sending volume over time is critical to avoid triggering spam filters.
  • Engagement Focus: Sending to engaged subscribers first boosts sender reputation.
  • Off-Peak Throughput: Sending emails off-peak times might help with throughput.

Key considerations

  • Monitor Metrics: Pay attention to bounce rates, spam complaints, and engagement metrics to identify and address any issues.
  • Segment Your List: Segment your list and only send to the most engaged users during the initial warmup phase.
  • Authenticate Properly: Ensure proper authentication (SPF, DKIM, DMARC) to improve deliverability.
  • Individual IP Warmup: If using multiple IPs, warm them up individually and consistently.
  • Valuable Content: Focus on sending valuable content that recipients want to receive.
Marketer view

Email marketer from Mailgun Blog shares that during IP warming, send a small volume of emails to your most engaged users first. Gradually increase volume and frequency over time, monitoring deliverability metrics closely.

January 2022 - Mailgun Blog
Marketer view

Email marketer from Email Marketing Forum explains that it’s important to segment your list and only send to your most engaged users during the initial warmup phase. This helps to establish a positive sender reputation and avoid being flagged as spam.

December 2024 - Email Marketing Forum
Marketer view

Email marketer from GMass Blog shares that sending time is less important than consistency and engagement. Focus on sending valuable content to people who want to receive it, and your sending reputation will improve over time, regardless of the specific time of day.

April 2021 - GMass Blog
Marketer view

Email marketer from Email on Acid Blog describes how IP warming is like introducing yourself slowly. Don't blast out emails immediately; build trust by gradually increasing volume and maintaining consistent sending habits.

February 2024 - Email on Acid Blog
Marketer view

Email marketer from SparkPost Blog advises senders to monitor their sending reputation closely during the IP warming process. Pay attention to bounce rates, spam complaints, and engagement metrics to identify and address any issues promptly.

June 2021 - SparkPost Blog
Marketer view

Email marketer from Reddit explains that the key to warming up a new IP is consistency. Start small, send to your most engaged subscribers, and slowly ramp up the volume. Avoid sudden spikes in sending, which can negatively impact your reputation.

November 2023 - Reddit
Marketer view

Marketer from Email Geeks shares that for her clients, she has them send when they would normally send as that's when their subscribers are used to receiving their emails.

May 2023 - Email Geeks
Marketer view

Marketer from Email Geeks shares that sending at times off the hour is helpful with throughput due to senders hitting right at the top of the hour, staggering delivery by a few minutes can help with throughput.

March 2022 - Email Geeks
Marketer view

Marketer from Email Geeks explains that send time should be irrelevant to reputation calculations and are likely to be rolled up to hourly or daily calculations, not tied to a specific hour. Also confirms that when warming IPs/reputation, it can be done any time of the day.

February 2024 - Email Geeks
Marketer view

Email marketer from Litmus Blog points out that if you're using multiple IP addresses, ensure you're warming them up individually and consistently. Don't overload one IP while neglecting others, as this can still hurt your overall reputation.

January 2022 - Litmus Blog
Marketer view

Email marketer from Email Service Provider Community mentions that gradual IP warming is crucial. Start with a small number of emails and slowly increase the volume over a period of weeks, monitoring key metrics like open rates and bounce rates.

March 2022 - Email Service Provider Community
Marketer view

Email marketer from SendGrid Blog suggests that you establish a consistent sending schedule. Start with a small batch of emails, and gradually increase the amount you send each day. Focus on sending to engaged subscribers first to boost your sender reputation.

October 2021 - SendGrid Blog

What the experts say
3Expert opinions

Experts generally agree that factors beyond send time have a greater impact on IP warmup and reputation. List quality, engagement, and proper authentication (SPF, DKIM, DMARC) are highlighted as more critical. While Microsoft OLC's 24-hour clock reset might be a consideration, understanding your audience and sending relevant content are key.

Key opinions

  • Authentication Matters Most: Proper authentication (SPF, DKIM, DMARC) has a greater impact than send time.
  • Engagement is Key: Consistent engagement is crucial for building a positive sender reputation.
  • List Quality: List quality is a significant factor affecting IP warmup and reputation.
  • Relevance Matters: Sending relevant content to your audience during the warmup process is crucial.

Key considerations

  • Microsoft OLC Reset: Consider the possibility of Microsoft OLC's 24-hour clock reset (possibly midnight Pacific Time).
  • Understand Audience: Prioritize understanding your audience and sending relevant content.
  • Engaged Recipients: Focus on sending to engaged recipients to establish a positive sender reputation.
Expert view

Expert from Word to the Wise discusses the importance of understanding your audience and sending relevant content to them during the IP warmup process. They emphasize that consistent engagement is key to building a positive sender reputation, and send time is less critical than sending the right message to the right people.

February 2025 - Word to the Wise
Expert view

Expert from Email Geeks agrees with Alex and shares about Microsoft OLC's 24 hour clock reset, guessing it's midnight pacific time.

March 2022 - Email Geeks
Expert view

Expert from Spam Resource explains that factors such as list quality and authentication are more crucial than the specific time of day you send your emails during IP warming. Focusing on sending to engaged recipients and ensuring proper SPF, DKIM, and DMARC setup will have a greater impact on your reputation.

September 2021 - Spam Resource

What the documentation says
5Technical articles

Email deliverability documentation consistently emphasizes that gradual IP warming is crucial for establishing a positive sending reputation with ISPs. This involves starting with a low email volume from a dedicated IP address and incrementally increasing it over time, focusing on consistent volume and frequency to avoid being flagged as spam. Sending to engaged recipients is also recommended.

Key findings

  • Gradual Increase: Warming up IP addresses involves gradually increasing email volume.
  • Positive Reputation: IP warming helps establish a positive sending reputation with ISPs.
  • Improves Deliverability: The process improves email deliverability.
  • Low Initial Volume: Starting with very low sending volumes is recommended.
  • Consistent Pattern: Establishing a consistent sending pattern is essential for legitimate recognition by ISPs.

Key considerations

  • Engaged Recipients: Focus on sending to engaged recipients to build a good reputation.
  • Consistent Frequency: Maintaining consistent sending frequency is crucial during the warming process.
  • Monitor Deliverability: Regularly monitor deliverability rates to avoid spam filters.
Technical article

Documentation from AWS explains that warming up IP addresses involves gradually increasing the volume of email you send using a dedicated IP address. This process helps establish a positive sending reputation with ISPs and improves deliverability.

January 2022 - AWS Documentation
Technical article

Documentation from Google explains that when starting to send from a new IP address, it's crucial to gradually increase sending volume to avoid being flagged as spam. They recommend starting with very low volumes and incrementally increasing over time.

March 2023 - Google Postmaster Tools
Technical article

Documentation from Microsoft details the importance of establishing a good sending reputation when using a new IP address. They recommend starting with a small volume of emails and gradually increasing over time, focusing on sending to engaged recipients.

April 2021 - Microsoft Docs
Technical article

Documentation from Mailjet highlights that a positive sender reputation is crucial for deliverability. IP warming helps build this reputation by establishing a consistent sending pattern that ISPs recognize as legitimate.

July 2023 - Mailjet Documentation
Technical article

Documentation from Elastic Email states that during IP warming, focus on consistent volume and frequency. They recommend a schedule that gradually increases the number of emails sent each day, ensuring that you're monitoring deliverability rates to avoid spam filters.

January 2025 - Elastic Email Documentation