Forgive me. It slipped my mind to send the documents for October so I'm sending them now. Please check the attached files. It would be great if you could send them back after signing.
I am very sorry. Since I forgot to send the October's document, now I am sending it. I am grateful if you verify the attachment and send it back to me with your sign.
毎月、書類にサインを頂戴するため「It would be very much appreciated if you could acknowledge receipt of this certificate.」という一文を添えて書類をメールで送っています。10月分の送付を失念しサインをいただけていないため、再度お送りしメールで返送してもらいたいという経緯です。