While adding accounts to the server, I have found that 2 accounts had problems with email. I did eventually get bouce messages with the following error :
Unable to open .qmail: access denied. (#4.3.0)
I’m not going to try again; this message has been in the queue too long.
Looking into this further, the .qmail file in the users home directories are all set with 0600 permissions. Changing the qmail file to 0644 solved the problem. Of the 7 accounts currently on this server, the problem occured on only 2 pf them, both had been imported from a cpanel backup on a remote server. So I’m not absolutely sure, but it looks like the cpanel import script is setting the permissions wrongly for the .qmail file.
The file was owned by the iworx user, and as qmail runs as differant users, world read permissions are required on the .qmail file.