My name is __________ (name) and I am writing on behalf of ____________ (company name). This email is in reference to the contract held between you and the company bearing contract number ___________ (mention contract number). This is to most humbly inform you that your contract is going to expire on __/__/_____ (date) and therefore, this is the reminder mail for the same.
In case you are interested in the renewal of the said contract, do contact me at _____________ (contact number). I expect to hear from you at the earliest.
If you have already renewed your contract, then kindly ignore this email.
_________ (mention name),
_________ (contact details)