Go to EShop -> Plugins -> Payments, then click on os_offline to edit it
Offline payment plugin is a special built-in payment plugin. It allows customers to place order and make payment for the order later (not at the time they checkout for the order) by bank transfer, cash on delivery, cheque, etc.
When customers choose offline payment to checkout products, the system will mark the order status as Processing and send a notification email to customers to tell them how to make the the offline payment (out side of system). After receiving payment from customer for the order, admin will login to backend of the site, go to EShop -> Sales -> Orders to change order status from Processing to Complete.
The Offline payment method also has different notification emails from other online payment methods. You should go to EShop -> System -> Messages to check the notification emails format of Offline payment method there to edit them.
Payment Fee = Payment Fee (Fixed amount) + Payment Fee (Percentage) * SubTotal / 100
Since version 2.5.5, we have already created duplicated offline payment plugins and include them into EShop package. If you want to have more duplicated offline payment plugins, simply find them in the folder eshop_unzip_first\duplicated-offline-payment-plugins, then go to EShop -> Plugins -> Payments to install one by one.