PayPal

From WHMCS Documentation

Instant Payment Notification (IPN)

For PayPal invoices to be automatically marked paid when you receive a payment you need to enable IPN inside your PayPal account. This is done in the My Account > Profile -> Instant Payment Notification Preferences (under Selling Preferences) area. You need to check the IPN box. As of April 2009, PayPal have removed the ability to leave the callback URL blank and so you must now set it to an url. It's not important what URL you use so set it to your system url http://www.yourdomain.com/whmcspath/

PayPal Subscriptions

Unless disabled in the PayPal gateway config, when a user views an invoice for a recurring product or service they will be shown a PayPal Subscribe button. This allows the user to subscribe so that their payment for that product or service is sent to you automatically each month and automatically applied to the invoices.

The subscribe button will only show on or before the due date of the invoice. This is to prevent the user signing up for a subscription late as then the invoice would be paid late every month.

Modify Subscriptions

By enabling Modify Subscriptions, customers will be given the option to create a new agreement or modify an existing one when going through the subscribe process. Saving you from having to cancel a subscription and create a new one.

When a client upgrades/downgrades modifying of the subscription does not occur at the time of the upgrade, it occurs on the next renewal invoice (when the client logs in to pay the new amount).

Due to limitations of PayPal's system, when modify is enabled, they ignore trial period amounts therefore prorata and promos can't be used.

Automated Refunds

As of version 4, you can issue refunds for PayPal payments directly from within WHMCS. Before you can do this however, you need to setup PayPal API access. The steps for doing this are as follows:

1. Login to PayPal
2. Go to Profile > API Access
3. Choose Option 2 - Request API credentials to create your own API username and password.
4. Choose Option 1 - Request API Signature and click Agree and Submit
5. Copy the username, password and signature that get provided and then click Done
6. Enter the details from the previous step into the WHMCS Payment Gateways config screen where requested

You will now be able to enter a refund and have it sent from PayPal at the same time from within the WHMCS admin area invoice management screen.