I recently had the same problem after an update to 7.5.1
I changed all the permissions on the .qmail file in the /home/e-smith/files/users/john.hankok/.qmail to 777 , and it stared to work.
I will address the permissions on all users once the system is running
I know 777 is a risk, but to get going as it is production server, that was the priority..once everyone was accessing their mail, I have managed to change all the files to the correct permissions
I recently had the same problem after an update to 7.5.1I changed all the permissions on the .qmail file in the /home/e-smith/files/users/john.hankok/.qmail to 777 , and it stared to work.