Parallels

Symptoms

I see the following error message during connection to my 'qmail' in Plesk system:

rcpt to:<user@domain.com>
421 fopen('users/assign') failed (#5.7.10) Permission denied
Connection closed by foreign host.

How to fix it?

Resolution

Standard access rights for the directory /var/qmail/users/assign should be the following:

~# ls -ld /var/qmail/users/assign
-rw------- 1 root root 738 Sep 24 16:53 /var/qmail/users/assign
~#

The reason of the mentioned failure is lack of 'suid' bit on these files:

~# ls -l /var/qmail/bin/smtp_auth
-r-xr-xr-x 1 root root 15172 Jun  8 12:48 /var/qmail/bin/smtp_auth
~#

~# ls -l /var/qmail/plugins/chkrcptto
-r-xr-xr-x 1 root root 15788 Jun  8 12:48 /var/qmail/plugins/chkrcptto
~#

adding this 'suid' bit should solve the problem:

~# chmod u+s /var/qmail/bin/smtp_auth
~# chmod u+s /var/qmail/plugins/chkrcptto

Very often such issue with lack of 'suid' bit might be due to failed Plesk upgrade, e.g. some of packages like 'qmail' were not upgraded correctly from earlier versions, and this caused this error.
To fix this problem please complete upgrade procedure of such packages to the latest version - this should help.