Thank you for your cooperation.
Dear [Recipient's Name],
For your security, I have password-protected the file. If you require the password, please reply to this email and I will provide it to you. Candy Cane53.rar
Best regards, [Your Name]
I hope this email finds you well. I am sending you a file titled "Candy Cane53.rar" which contains [ briefly mention the content of the file, e.g. "some festive holiday-themed documents"]. Thank you for your cooperation