As the name clearly states, a donation letter is generally written to inform about the details of donation and the reason for donation to a particular organization. First you need to inform the amount you are going to donate and then the reason why you choose the organization for donation. Check the template given below.
Dear [name of receiver],
I am writing this letter on behalf our official members and take pleasure to inform you that we decided donate a sum of $10,000 to your organization.
Recently we came to know about your organization and various social welfare activities carried out by your organization. So, we wanted to join hands with you and help the needy people in time.
You can use this money for all your social welfare events and programs. You can also use our banner to advertise your event, which may give you a upper edge in reaching common people.
Waiting to hear your reply!!
Thanks and regards