Study of email subject lines
Research by Yotpo of 200K stores and 163M orders discovered the impact of various elements in the email subject line on the number of reviews obtained:
1) Exclamation point (!)
- Health & beauty: +30.4%
- Food & tobacco: +83.5%
- Sport: -10%
- Electronics: 30%
2) Question mark (?)
- Electronics: +21.7%
- Apparel: +23%
- Health & beauty: -6.7%
3) Store name
- Health & beauty: +14%
- Sport: +13%
- Electronics: +15.5%
- Food & tobacco: -74%
4) UPPERCASE
- Electronics: +26.7%
- Health & beauty: -39%
- Sport: -21%
5) Incentives (coupon, discount, sale)
- Health & beauty: +31.5%
- Electronics: +16.8%
- Apparel: +8.7%
- Food & tobacco: +106%
Additional resources
- 3 samples of Product Review Request emails by Jilt (towards the bottom of the article)
- Examples by Reviews.io
- A few more examples and guidelines by Campaign Monitor