Email templates for new user signup

Hi,

What the best practice to modify/customize the text in the email templates for new user signup ? I am using a mailgun equivalent to send emails.

I mean modyfing this:

Welcome

Blog Name is using Ghost to publish things on the internet! Admin User has invited you to join. Please click on the link below to activate your account.

No idea what Ghost is? It’s a simple, beautiful platform for running an online blog or publication. Writers, businesses and individuals from all over the world use Ghost to publish their stories and ideas.

Have fun, and good luck!

Thanks,

There’s not currently a way to change those email templates without modifying core.

Thanks for the swift answer.
Can I assume that I need to fork Ghost and install on a stand alone server ?