There are several effective methods to collect product feedback through email: 1. Surveys: Send out a survey link post-purchase to gather structured feedback. 2. Personalized Requests: Email individual customers asking for their thoughts on a recent purchase. 3. Automated Follow-ups: Set up automated emails that trigger after a product is delivered, asking for feedback. 4. Incentivized Feedback: Offer discounts or rewards in exchange for completing feedback forms.