can I define a field object on layout so that the text inserted behave as a hyperlink (ie opening mail client when selected) ?
You can define the field object as a button. Your script could insert the cursor in the event that the field is empty, otherwise go to the URL. You would need a second button somewhere to edit the field. You could also simply put a "go" button next to the field.
If you want to include links amongst other text within a text field and have only the link clickable, you would need to use a calculation to transform your field into html and present it in a web viewer.
I like to add a small e-nvelope icon on a button next to the email address. This sends the email to that "selected" person.
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