I propose a case to understand how to move. I am a small hotel in the fair area, I would like to send a simple presentation email to the participants at the fair, retrieving the general emails (info @) from the fair site. I would simply like to present my hotel with a link to my site. Can I send the communication or do I have to have consent before?
This depends how and where did you get the email addresses from. Usually, when collecting personal data a Privacy Notice needs to be presented to the data subjects. The Privacy Notice informs data subjects, among other things, for what purposes the data will be processed and which is the lawful ground for processing. Usually, for marketing purposes the lawful ground is either consent of legitimate interest. If you want to find out more about consent and legitimate interest, check out our webinar “How GDPR Affects Marketing Practices” (https://advisera.com/eugdpracademy/webinar/how-gdpr-affects-marketing-practices-free-webinar-on-demand/).