Greetings of the day!
Similar to letter writing, an email follows the main flow of subject, core matter, time frames if any, contract type (permanent or contractual), and any other points like the reason for change, any commercial (fees) implications as the basic. As your query is very brief, I am sharing what I think may help you frame your email/correspondence. Hope this helps. If not, please do share more details on your query to assist.