I'm on Debian 8 and not sure what I have done as whenever I try and send an email using Roundcube it says there was an error sending the message, so I checked the logs and found: postfix/sendmail[22146]: fatal: open /etc/postfix/main.cf: Permission denied Everything was working a couple of days ago and I have not changed anything since, not even installed updates. So I tried: sudo chown root:root /etc/postfix/main.cf sudo chmod 0644 /etc/postfix/main.cf Still no luck after restarting both Postfix and Dovecot When using `ls` to view permissions: -rw-r--r-- 1 root root 2363 Jun 3 23:32 /etc/postfix/main.cf Here are my permissions for `/etc/postfix` drwxr-x--- 3 root root 4096 May 30 19:44 . drwxr-xr-x 101 root root 4096 Jun 4 00:58 .. -rw-r----- 1 root root 329 May 30 18:08 dynamicmaps.cf -rw-r--r-- 1 root root 2367 Jun 4 00:40 main.cf -rw-r----- 1 root root 6046 Jun 1 13:39 master.cf -rw-r----- 1 root root 149 May 30 19:43 mysql-virtual-alias-maps.cf -rw-r----- 1 root root 143 May 30 19:44 mysql-virtual-email2email.cf -rw-r----- 1 root root 139 May 30 19:45 mysql-virtual-mailbox-domains.cf -rw-r----- 1 root root 139 May 30 19:52 mysql-virtual-mailbox-maps.cf -rwxr-x--- 1 root root 28047 Apr 29 17:01 post-install -rw-r----- 1 root root 20281 Apr 29 17:01 postfix-files -rwxr-x--- 1 root root 8861 Apr 29 17:01 postfix-script drwxr-x--- 2 root root 4096 Apr 29 17:01 sasl Really not sure what to do now as my email server has basically been unusable since this happened.