Do it! If you fail to pick up the certified letter,it is sent back to the merchant. The merchant can then proceed as if you had gotten the letter but ignored it. The letter must give you 10 days to pay the check. If you fail to do so, the merchant can take the letter and the check to the district attorney or county attorney to file criminal hot-check charges against you. Not only will you have to pay the check, but also you can be arrested, have to pay a large fine, and end up with a criminal record.
Some merchants use a check collection company before they send the certified letter. Closed check account can be treated just like a hot check or worse. Most merchants will send you a certified letter, but they are not required to do so. Hot checks of $750 or more can be treated as third-degree felonies and are a very serious matter. Even a check of under $20 is still a Class C misdemeanor, as a frame of reference. A lawyer might need to get involved if you find yourself in such a situation.