The consensus among experts, email marketers, and documentation sources is that you should continue sending emails from your old ESP while warming up a new IP address. Overlapping the use of both ESPs is a best practice for maintaining a consistent sending presence, preventing a sudden drop in email volume, and preserving your sending reputation. Focus on sending to your most engaged subscribers from the new IP to establish a positive reputation with ISPs, while gradually reducing the volume of emails sent from the old IP. It is crucial to monitor deliverability metrics for both IPs and inform subscribers about the change. Delay moving revenue emails to the new IP until warm up is complete.
10 marketer opinions
When warming up a new IP address, it's generally recommended to continue sending emails from your old ESP. This helps maintain a consistent sending presence and avoids a sudden drop in email volume, which can negatively impact deliverability. The key is to transition gradually, overlapping the use of both ESPs. Focus on sending to your most engaged subscribers from the new IP to establish a positive sending reputation, while reducing the volume of emails sent from the old IP over time. Monitoring the performance of both IPs, including open rates and bounce rates, is crucial during this process.
Marketer view
Email marketer from Iterable explains that you should segment your audience during IP warm-up. They say you should start by sending to your most engaged subscribers to establish a good reputation with ISPs.
4 Mar 2023 - Iterable
Marketer view
Email marketer from Email Marketing Forum states that it is important to monitor the performance of both IPs, watching open rates and bounce rates of both sets of sends, and if things are going well, slowly ramp down the old IP as the new one increases
5 May 2025 - Email Marketing Forum
6 expert opinions
Experts generally recommend overlapping migration periods when warming up a new IP address with a new ESP. This means continuing to send from your old ESP, focusing on less engaged subscribers or specific types of emails like revenue emails, while sending to the most engaged subscribers from the new IP. Sending a notice to subscribers about the change is also suggested. It is best not to stop sending completely from your old ESP to keep a consistent sending volume.
Expert view
Expert from Email Geeks suggests sending a notice saying "we are making changes to improve our services, and our [from address / other ] is changing be sure to look out for [new thing] here".
20 Aug 2024 - Email Geeks
Expert view
Expert from Email Geeks recommends starting with the most engaged subscribers on the new IPs and sending to less engaged subscribers from the old IPs, and not letting people forget you.
18 Aug 2024 - Email Geeks
4 technical articles
Technical documentation from various sources emphasizes the importance of a gradual approach when warming up a new IP address. When transitioning to a new ESP, it's crucial to gradually increase sending volume from the new IP while phasing out the old ESP. Avoiding sudden changes in sending volume is key to maintaining a consistent sending reputation and preventing deliverability issues. Starting with small volumes enables you to monitor deliverability and address any issues that arise.
Technical article
Documentation from Microsoft shares that you should avoid sudden changes in sending volume. Gradual increases and decreases are preferred to maintain a stable sending reputation and ensure deliverability.
5 Nov 2023 - Microsoft
Technical article
Documentation from Google Postmaster Tools explains to gradually increase sending volume when starting to send email from a new IP address. Starting with small volumes allows you to monitor deliverability and address any issues that arise.
20 Dec 2023 - Google Postmaster Tools
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