How to send a payment receipt email
Payment receipts can be sent from the Payment page.
Go to Manage > Financials > Payments and locate the payment. Hover over it and click on the far right blue down arrow. Select the "View" command.
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You will see the Edit Payment page. Click on the "More" button in the bottom right, and select the "Send Payment Receipt" command.
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You will see a confirmation message. Select "Send Email" to send the message.
Note that you can customize the text of the email by going to Communications > Settings > Notification Templates and editing the appropriate "Payment Receipt" email template.