If a donor wants to donate funds/ goods in kind and wishes to stay anonymous, you can still log the monetary values that have been donated under the anonymous donor and issue a receipt.
Keep in mind that because the donor is anonymous and the information given may be limited, a Section 18A certificate cannot be issued for this type of donor.
After you have issued a receipt for the anonymous donor you can email the receipt to the donor or you can download and even print it for them.
However, if you want to email it to the anonymous donor you will have to physically enter their email address every time.