Respected Sir/madam,
I would like to most humbly inform you that I am working as a _________ (designation) in your reputed company for the last ________ (mention duration).
I write this email with the utmost respect to inform you that I am willing to work overtime as __________ (mention reason for overtime). In this regard, kindly allow me to work overtime from __/__/____ (start date) to __/__/____ (end date) from __:__ (time) till __:__ (time).
Hope you consider my request. I look forward to your quick response in this regard.
Yours truly,
___________ (Mention name),
___________ (Mention department)
___________ (Mention employee ID),