Whoops. There's an issue that I hope that you won't incur in bill paying. With a little selectivity, it can be avoided.
There are two types of transactions that bill paying systems process. One is direct pay, and the other is indirect pay.
In a direct pay, payees enter into agreements with your financial institution to alllow the transfer of funds directly from your account to the payee's account. When you search for your payee in their list of payees, you will find out if this is a direct pay. Your financial institution has the payee's account number behind the scenes.
In an indirect pay, also called a deferred pay, the payee has not entered into an agreement with your financial institution. When you search for your payee, you will find out that this is not a direct payee. Your financial institution does not have the payee's account number. When you pay these bills, a check is printed with your name and the payee's account number and sent via snail mail. You are normally forewarned to allow five or more working days for receipt and posting of these transactions (current postal schedules). Now here's where the problems start with indirect pays.
By example, I will relate an incident that happened to me. I had my car repaired at at local shop. The shop later called me to say that the bill was short $15.00, so I said that I would use bill pay for that amount.
The shop wasn't in the direct pay list, so I set up an indirect bill pay with their address, and paid them right then. A month later, I received a phone call from the shop that the $15.00 never arrived. So, I checked my bill pay, and the bill had been paid the bill on the same day as my phone conversation with them. I called up my financial instiitution. They told me that, per my agreement with them, as soon as the bill paying system marks the bill paid, they are no longer responsible, even if the check hasn't left the building yet. My options, I was told, were (1) place a stop order on the check and pay them their normal fee (~$30.00), or (2) wait until the check goes stale (several months).
My options were then (1) to pay again on bill pay, (2) to snail mail a check, (3) to drive a check to the auto repair shop, or (4) to let the bill pay check float out there somewhere. Paying again via bill pay would only complicate the issue. So, I drove a check there, and left the outstanding check float open in my Quicken for several months.
Read your financial terms. I think you will find that they will abrogate any responsibility once you click, "Pay". Stop orders are a money maker for them. If this was a large check, such as a mortgage payment, I would have had to eat the $30.00, or leave a large balance to cover the duplicate floating check with an ensuing recovery hassle.
Personally, after this very bad experience with financial institution terms, I have completely stopped using bill pay. I only use auto transfer, credit card or PayPal. If I were to use bill pay, I would only use direct payees - no exceptions.