I insert a field with {subtag: namefield} which contains a link to a url. Can I activate the link in the newsletter? It's possible?

Hi,

Sure you can! Switch your editor to source code and add this:

<a href="{subtag: YOURFIELDNAME}">{subtag: YOURFIELDNAME}</a>

or if you do not have the protocol in your field:

<a href=https://"{subtag: YOURFIELDNAME}">{subtag: YOURFIELDNAME}</a>