Data protection on the Internet is an important issue nowadays because it is very important that someone's confidential information is always protected and stored and is not vulnerable to security breaches.
Privacy is very important when it comes to email marketing; because people need to know that you are ethical and that you will never sell their contact information to third parties in the future (there are laws that prohibit it).
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A small symbol and a statement that says "We take your personal data seriously" shows that person that you are a professional and that it is good for them to trust you.
This is very important if you want to collect more personal information, not just their email address, for example by making a survey based on the types of products you offer on your list.