Hello, I have the same problem, or sort of. Let me explain: On my MBP, I have only one gmail account configured in Mail. Smart mailboxes are working fine and the Account parameter is of course set to the gmail account but it works. On my MBA, I have 2 gmail accounts and 1 iCloud account configured in Mail. The account parameter in smart mailboxes can not work with 1 of the 2 gmail accounts. Each time I try to set up with the gmail account I want, It is reset with the iCloud account and though, the smart mailbox does not work as I want to. Since I add on the MBP the iCloud mail account as a second mail account, the account parameter of the smart mailboxes is also reset to the iCloud mail account as default parameter. -> smart mail box does not work properly. When I delete the iCloud mail account and have only the gmail account, everything restarts to work properly in the smart mailboxes.... Ìt seems when there is an iCloud account configured, smart mailboxes consider the iCloud account as the only possible value for the account parameter. Can someone else confirm this behavior? I googled but did not find any other website dealing with this topic. I hope this can help to solve this issue on Apple's side.