Determining an adequate sample size depends on several factors:
Objectives: Clearly define what you aim to achieve with your campaign. Your sample size should be large enough to detect meaningful differences or trends. Confidence Level: Choose a confidence level (commonly 95%) that indicates how sure you are that your results are accurate. Margin of Error: Decide on an acceptable margin of error, which reflects the range within which you expect the true results to fall. Population Size: Consider the total size of your email list. Larger populations generally require larger samples to yield reliable results.