What is the minimum email batch size suggested for IP warmup?

For effective IP warmup, starting with a relatively small number of emails is advisable to build a positive sending reputation gradually. The warmup process involves sending increasing volumes of emails over a defined period to establish trust with ISPs and avoid being flagged as spam.

By initiating with a smaller batch size, marketers can monitor engagement metrics such as open rates and click rates closely. This close monitoring helps identify any issues early on—such as delivery problems or negative responses—which can be addressed without jeopardizing the entire sending reputation. A larger batch size at the outset may lead to overwhelming responses that could negatively impact deliverability.

Thus, the approach of starting small allows for a controlled escalation in email volume, ensuring that ISPs see consistent behavior from the sending IP, which is crucial for warming it up successfully.