Each email that the system sends on your behalf is based on a template.
You can edit a template by clicking your employer name in the man navigation and going to Settings -> Templates.
All of your email templates, as well as PDF templates, are listed here.
Select the template you want to customise from the list.
Tick the box labeled 'Customise this template'.
You can now edit the HTML used for this template. You'll see a list of Tokens at the bottom of the page. These are used like a mail merge. For example when you enter
in a template that supports that token then it'll be replaced with the relevant Employees first name when it is parsed.
If you want to abandon your changes and revert to the default content for the template simply un-tick the 'Customise this template' checkbox and click 'Save Changes'
To customise the surrounding HTML and CSS see Customising Emails