Do I need to ask my subscribers for permission again?

Proof of consent

Under GDPR, it is important to clearly prove that the people you want to email have consented to it.

In the case of customer relations, you need to be able to show when and how this person became a customer.

Is a consent campaign really necessary?

If you prove that you were given consent, you do not need to ask again. So, if you can look up that someone made an order, requested information, or subscribed to your newsletter, asking for consent again is redundant.

If you cannot remember exactly how a subscriber ended up in your subscriber list, it might be required to ask them for consent again.

You can find the link to a page explaining to you how to create such a campaign here.