If a customer requests a stop payment on a check through the internet, is it required to have a signed request within 14 days or is the internet request enough?.

I hate answering questions with "That depends," but it does in this case.

If your customer is using your bank's Internet Banking service to send you the stop order, you could readily adopt and disclose a policy that says you won't require a manually signed stop order to ratify the electronic request (since the customer had to log in to a presumably secure server first).

If the customer is sending you a public server e-mail without some form of sender authentication, you might want to continue requiring a manually signed stop order.

Via the Net is not necessarily "in writing". As John notes, authentication of the customer and therefore a validation of who the requestor is, is better done through your Internet banking product or if you have a PGP system in place that contains a digital signature. In this case, you will have agreed to these terms before.

The UCC requires a follow-up, "in writing". But that doesn't necessarily mean your state's UCC does or that you have not allowed a variance in your agreement with the customer.