@coja Welcome to the Netlify community.
Did your e-mail provider tell you the IP address? If so, you should be able to create a new MX record in your Netlify DNS. however, you currently have “mail.nuebo.ro” as your e-mail provider, which means that you are trying to run an e-mail host on Netlify, which is never going to work.
Typically, if you want to run custom-branded (such as firstname.lastname@example.org) with a service such as Netlify, you would use Gmail or some other service that handles all the e-mail part of it and allows you to send and receive through your custom domain.
If you don’t need custom-branded e-mail (that is, if coja@iCloud.com) is fine but you want to present the world with a custom-branded e-mail, then you’ll need to set up something like Improvmx to forward your custom-branded e-mail to your regular e-mail address and “send mail as” from Google. FWIW, Improvmx also has a paid tier that allows you to send and receive e-mail from any custom-branded address.
The only thing you cannot do is run an e-mail service on Netlify, which is how you have it set up now.