Zorathustra,
As a bank lawyer for a Fraud Department, I can assure you that your bank's position is both reasonable and necessary and in line with many other banks. I know it is an inconvenience for you but, unfortunately, along with the incredible convenience the Internet has provided has come a huge amount of fraud and the wonderful world of "Nigerian" type scams that a surprising number of people fall prey to. These type scams are largely dependent on the victim thinking that whats looks to be a valid cashier's check, Official Check, or Postal Money Order is geunine when, in fact, they are not.
Even in non-counterfeit situations (e.g., NSF checks or "account closed" check fraud), when checks or instruments are drawn on foreign banks, all of the rules and protections afforded both customers and banks by Reg CC and the Expedited Funds Availability Act or no longer applicable for the most part. Foreign check clearing is a very risky proposition for the bank and the customer since the foreign bank may return items for up to a year while a domestic bank is subject to much stricter time limitations.
As such, even after that 45 day hold expires, that check may come back to haunt you and be returned against your account. I feel bad for many bank customers who do not understand the difference between "available funds" and "good funds." For example, with US drawn checks, Reg CC and the Expedited Funds Availability Act require that a bank make funds "available" to you in accordance with a strict prescribed time schedule (unless an exception applies). One example is a check drawn on a local bank and deposited in a different local. In this case the bank MUST make the funds available in two banking days unless a Reg CC exception applies. BUT, making them "available" does not mean the funds have cleared and are "good funds" or that the check can't be returned. This check may still be returned after the funds were made available (assuming compliance with the return provisions of Reg CC).
So, many people think because the funds are "available" the check is not subject to being returned and they are shocked if and when it happens.
Thus, a word to the wise, be careful who you deal with and how quickly you spend the funds from a check you receive unless you know the person who gave it to you for it may come back after you have spent the $$$$. Again, even after the 45 day hold, that foreign check may come back 11 months later and the bank will ofset that loss or sue you for the balance they cannot get from your account.
Long, I know, but I hope this helps.