Answer:
There are six listed exception hold reasons in Reg CC. These are: large deposit, repeat over drafter, redeposited item, new account, reasonable cause to doubt collectibility, and emergency conditions. Some people have argued that a check that could not be verified is reasonable cause to doubt collectibility. While not written anywhere, I know many regulators have taken issue with this and contend that simply not being able to verify a check does not rise to "reasonable cause to doubt collectibility."
First published on BankersOnline.com 10/11/10