Who can do this: everyone. Templates are shared with the people you choose under Available for.
Save the emails you send with your lists, so you don't write them each time.
Create a template
Go to Settings > Email templates.
Click Create new template. Or pick a template and click Duplicate.
Write the subject and message. Insert placeholders where the details change, for example List name, First name, List URL and Author first name.
Choose Styled email or plain text, and who the template is Available for.
Save, then click Preview to check it.
Use a template
When you share a list, click Email templates in the share dialog and pick one. You can still change the text before you send.
Good to know
The company default template has the subject "New candidates for List name shared by Author first name".
Keep List URL in the message. It's the link your client clicks.