Summary
Warming up a list of 100k contacts is generally recommended, especially if the list is old, hasn't been mailed to recently, was acquired through questionable means, or if you are using a new IP address or domain. The consensus is that warming up helps establish a good sender reputation, prevents being flagged as spam, and improves deliverability. A gradual increase in email volume, starting with small batches (e.g., 1k, then 10k), is crucial, along with closely monitoring deliverability and engagement metrics. List cleaning (removing invalid addresses), proper authentication practices, segmenting the list based on engagement history, and IP/domain warmup are also key. If the list is consent-based and actively mailed to, a warmup might not be necessary. Hubspot provides an automatic warmup feature with its dedicated IP option.
Key findings
- Reputation Protection: Warming up is vital for establishing a positive sender reputation and minimizing the risk of being marked as spam.
- Gradual Ramp-Up Crucial: A gradual increase in email volume over time is essential.
- List Age & Source Impact: The age and source of the list significantly affect the need for warming up. Older or questionably sourced lists need more attention.
- Authentication is Key: Following email authentication best practices is critical for deliverability.
- IP/Domain Reputation: Think about your domain and IP address when warming up.
- Hubspot Auto Warmup: If you purchase a dedicated IP address through HubSpot, there is an automatic warm up feature.
Key considerations
- List Hygiene: Before warming up, clean the list to remove invalid or inactive addresses to reduce bounce rates.
- Segmentation Strategies: Segment the list based on engagement history and tailor content accordingly during warmup.
- Monitor Engagement & Deliverability: Continuously monitor engagement metrics and deliverability rates to identify and address issues.
- Consent & Frequency: If recipients have given consent and are mailed to frequently, a warmup might not be needed
What email marketers say
12 marketer opinions
When dealing with a list of 100k contacts, a warm-up process is generally recommended, especially if the list is new, old, hasn't been used recently, or was acquired through questionable means. This helps establish a good sender reputation. It's best to start with smaller batches of emails (e.g., 1k, then 10k) and gradually increase the volume over time, while closely monitoring deliverability and engagement metrics. Segmentation, list cleaning (removing invalid addresses), and IP/domain warm-up are also key.
Key opinions
- Sender Reputation: Warming up is vital for establishing a positive sender reputation, reducing the risk of being flagged as spam.
- Gradual Increase: A gradual increase in email volume is crucial, starting with smaller batches and progressively increasing.
- List Age/Source: If the list is old, inactive, or of questionable origin, warming up becomes even more critical.
- IP/Domain Reputation: Warming up might refer to your sending IP or domain's reputation, not just the list itself.
Key considerations
- List Cleaning: Before warming up, ensure the list is cleaned of invalid or inactive addresses to prevent high bounce rates.
- Segmentation: Segmenting the list and sending targeted content during the warm-up process can improve engagement.
- Monitoring: Closely monitor deliverability and engagement metrics throughout the warm-up process to identify and address any issues promptly.
- New IP/Domain: If you are using a new IP address or domain, a warm-up process is definitely necessary.
Marketer view
Email marketer from Woodpecker Blog shares that to think about your domain and IP address as a newly-hired employee, you need to gradually show you are someone to be trusted by sending small amounts of emails and seeing who responds.
27 Apr 2024 - Woodpecker Blog
Marketer view
Marketer from Email Geeks shares a rule of thumb to send to 1K first, and if everything is ok, 10K to confirm it is indeed ok when testing a new list.
2 Feb 2025 - Email Geeks
What the experts say
3 expert opinions
Experts offer varied perspectives on warming up a list of 100k contacts. If the list is consent-based and actively mailed to, a warmup might not be necessary. However, list age is a significant factor; if the list is old or hasn't been mailed to recently, a warmup is essential to re-establish engagement. Additionally, it's important to treat new IPs and domains with caution and avoid sending to excessively large lists initially to prevent blocklisting.
Key opinions
- Consent & Frequency: If recipients have given consent and are mailed to frequently, a warmup might not be needed.
- List Age Matters: List age is a crucial factor; older, inactive lists require a warmup process.
- New IP/Domain Caution: Treat new IPs and domains cautiously, avoiding sending to excessively large lists initially.
Key considerations
- List Segmentation: Consider segmenting your list based on engagement history and sending targeted content.
- Monitor Engagement: Closely monitor engagement metrics during the initial sends to identify any issues.
- List Hygiene: Ensure your list is clean and free of invalid or inactive addresses.
Expert view
Expert from Email Geeks questions why a warmup is needed, suggesting if the recipients are consent-based and mailed to frequently, it shouldn't be necessary.
8 Apr 2022 - Email Geeks
Expert view
Expert from Word to the Wise shares that it is important to think about your IPs and domains like you are just starting out and not to send to a list size that is too large to ensure it doesn't get you on any blocklists.
22 Nov 2023 - Word to the Wise
What the documentation says
5 technical articles
Documentation from various platforms like Google, Microsoft, SparkPost, Mailchimp and Hubspot emphasizes the importance of warming up IPs, following authentication best practices, and list management for bulk senders, particularly those with large lists (like 100k contacts). Warming IPs helps build a positive sending reputation to avoid blocks and improve deliverability to services like Gmail and Outlook. A gradual ramp-up in sending volume and monitoring bounce rates are also recommended. Hubspot offers automatic warm up with a dedicated IP
Key findings
- Authentication is Key: Following authentication best practices is critical for bulk senders.
- Reputation Matters: Building a positive sending reputation is essential for deliverability.
- Gradual Ramp-Up: A gradual ramp-up in sending volume is advised, especially when starting with a new IP.
- Monitoring Essential: Continuous monitoring of bounce rates and sender reputation is necessary.
- Hubspot Auto Warmup: If you purchase a dedicated IP address through HubSpot, there is an automatic warm up feature.
Key considerations
- Dedicated IP Warmup: Warming up dedicated IPs is crucial to establish a positive sending reputation.
- List Management: Proper list management practices are necessary to improve deliverability.
- Bounce Rate Monitoring: Monitor bounce rates to identify and address deliverability issues promptly.
Technical article
Documentation from Microsoft Postmaster explains that to improve deliverability, especially when sending to large lists, proper authentication and list management practices are necessary, recommending gradual ramp-up and monitoring bounce rates.
3 Aug 2021 - Microsoft Postmaster
Technical article
Documentation from Hubspot explains that if you purchase a dedicated IP address through HubSpot, there is an automatic warm up feature so you can start sending emails right away.
21 May 2024 - Hubspot
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