If you have already recorded a payment on the invoice you can easily send the payment receipt by selecting the invoice > payments tab within the invoice > select the 3 little dots/icon to the right of the payment > select the option > send payment receipt

Once sent your client will receive an email with the payment receipt.

Record a payment on the invoice via the Invoice > Record Payment tab > record payment

Enter in the amount, currency and date of payment.

Once you have entered the payment amount and date > Select 'Record Payment.'

You can also record the payment on the invoice via the invoices tab > select the record payment option to the right of the invoice

Once you select record payment you will notice a pop up window appear confirming the recorded payment and an option to send a payment receipt.

At this point you can select to send a payment receipt simply select > Send Receipt

A new window will appear with options to edit the default payment receipt email message as well as add or turn off email addresses for your recipients.

You can also select to add recipients to send the payment receipt to by selecting the grey plus + symbol and adding in additional email addresses

You can also select to turn off the email going to certain recipients by selecting the contact name highlighted in green for the recipient email address.

Once you are happy with the payment receipt you can simply select > Send Receipt