Payment Options when sending the pay online link via email
When using a template that utilizes the pay online tag, or the pay online button, the system will present the option to pay a partial payment to the customer. The option to allow for a partial payment will be located directly beneath the subject field:

If no action is taken, the default (no check in the checkmark box) is to only accept a full payment when paid via these online links. Per expectation, the Online payment portal will appear like this when no action is taken regarding these controls. We can see that reflected in the "Total to be Charged" field:
If no action is taken, the default (no check in the checkmark box) is to only accept a full payment when paid via these online links. Per expectation, the Online payment portal will appear like this when no action is taken regarding these controls. We can see that reflected in the "Total to be Charged" field:
However, if wanting to accept the total or a different amount, this is where interacting with this setting will come into play -

The two choices that are allowed in addition to the invoice total due are :'This Percentage' and 'This exact amount':

As an example of how the Online payment portal changes to allow these options for your customers, assuming a $50.00 invoice total due, with the option selected of 'this percentage' at 25%, would result in the payment portal allowing these selections:
The two choices that are allowed in addition to the invoice total due are :'This Percentage' and 'This exact amount':
As an example of how the Online payment portal changes to allow these options for your customers, assuming a $50.00 invoice total due, with the option selected of 'this percentage' at 25%, would result in the payment portal allowing these selections:
If we were to utilize the "this exact amount" option, using the same $50.00 invoice total due and 25 for the exact amount, the online payment portal would reflect the following:
Please note that there is a prerequisite to include the PayOnlineLink invoice email communication template for these functions to be available.