How can I translate emails that are sent

I would like to know where I can find the source files for the emails that ghost sends out using mailgun. I would like to translate the text in these emails.

Emails such as this one:

Hey there,

You’re one tap away from subscribing to example.com — please confirm your email address with this link:

[Confirm Email Address]

For your security, the link will expire in 10 minutes time.

All the best!
The team at Example.com