If donor provided an email address at the time of transaction process then receipt will be automatically sent to the donor. Please check and make sure that email address is available for the donor's record:
In order to resend the donation receipt to the donor please follow below steps:
Go to Donations > Transactions > Search for the donor > Select date filter > Hit Search > Click on View against the relevant transaction > Click on Save & Email
The email will be sent on the provided email address. Below screen shots are for reference.
