Sampling Bias: When the sample of email recipients is not representative of the entire audience. Confirmation Bias: When marketers interpret feedback in a way that confirms their pre-existing beliefs. Question Framing: The way questions are framed in surveys can lead to certain types of responses. Self-Selection Bias: When only a specific segment of recipients chooses to respond to surveys or feedback requests. Non-Response Bias: When recipients who do not respond to surveys differ significantly from those who do.