You can recreate qmail’s queue by following the steps given below, but while recreating all the current messages will be removed from the queue and cannot be restored. So it is better to take backup of messages before starting.
Steps:
1. log into server and stop qmail – #/etc/init.d/qmail stop
2. cd /var/qmail/queue
3. rm -rf info intd local mess remote todo
4. mkdir mess
5. for i in `seq 0 22`; do
mkdir -p mess/$i
done
cp -r mess info
cp -r mess intd
cp -r mess local
cp -r mess remote
cp -r mess todo
chmod -R 750 mess todo
chown -R qmailq:qmail mess todo
chmod -R 700 info intd local remote
chown -R qmailq:qmail intd
chown -R qmails:qmail info local remote
6. Now start qmail— /etc/init.d/qmail start

To create email account on an Android Mobile Device, please follow the below steps.
1. From the Home screen, click on the gray Application button.
2. Click on Email.
3. Then Next.
4. Using the keyboard, enter:
Email Address
Your full email address
Password
Your email password
5. click Next.
6. Click IMAP Account or POP Account.
7. Enter the following:
Username
Your full email address
Password
Your email password
IMAP/POP Server
Your Incoming POP or IMAP Server
(Optional) Security type
SSL (Accept all certificates)
IMAP/POP path prefix
No changes required
Incoming port
IMAP without SSL –143
IMAP with SSL –993
POP without SSL –110
POP with SSL –995
8. Tap Next.
9. In Outgoing server settings type:
Server name
Your Outgoing SMTP Server
(Optional)Security type
SSL (Accept all certificates)
Outgoing port
Without SSL – one of the following:25, 80, 3535, 587
With SSL –465
Require sign-in
Select to enable
Username
Your full email address
Password
Your email password
10. click Next.
11. Choose desired Account Settings.
12. Choose desired additional settings on Set up email.
13. Click on Done.

If you want to disable redirection to SSL connection while accessing WHM, cPanel, Webmail, please follows these steps.
Login to WHM >> Tweak Setting >> Uncheck the following options under Redirection.
Always redirect users to the ssl/tls ports when visiting /cpanel, /webmail, etc.
Also you have to uncheck the following option under Security in Tweak Settings.
Require SSL for all remote logins to cPanel, WHM and Webmail. This setting is recommended.
Also you can disable those options from the shell.
SSH to the server as root.
Open /var/cpanel/cpanel.config and set the following options to 0 (zero).
alwaysredirecttossl
requiressl
—-
alwaysredirecttossl=0
requiressl=0
—–
Save the file and exit.

If you are trying to move large number of files such as more than 50000 files using the command mv, you will get the error given below.
[root@server /]# mv * /path/to/move
“/bin/mv: Argument list too long”
In such cases, you can use the command given below to avoid this error ,

find /path/to/file -type f | xargs -i mv “{}” /path/to/move

If your server are having multiple IP address and you want to send each emails in different IP, then please follow the steps. This is used to maintain the ip reputation. Also, please make sure that this is not used for spamming.

1. vi /etc/exim.conf
2. Search for the line : interface =
3. Replace this line with interface = xxx.xxx.x.1${eval:${substr{-2}{1}{$tod_zulu}}%9+1}
4. If your server is having ip’s from xxx.xxx.x.11 to xxx.xxx.x.20 , you can use above line.
+1 is is the starting ip ie xxx.xxx.x.1’1′ and %9 is the increment value ie 11(xxx.xxx.x.11) to how much. Here it is 20 (xxx.xxx.x.20)