I am going to write to sponsor for thanking them and send invoice. please correct.
Thank you once again for [company name] kind contribution. Our research paper Issue II – Electronic copy has been uploaded to our official website while the hard copy is in process of printing that will take another week. You can use the following link for download or view it from our website:
Further, I have couriered/sent you the invoice for [company name] sponsorship for advertisement in Research Paper
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.