First create a file which contains all the user name. Something like this:

nurealam
nayeem
mrahman
farid
rubi
sankar

Save the file as userlist.txt. Now create the following bash file:

#!/bin/sh
for i in `more userlist.txt `
do
echo $i
adduser $i
done

Save the file and exit.

chmod 755 userlist.txt

Now run the file:

./userlist.txt

This will add all the users to the system. Now we have to change the passwords. Let’s say we want username123 as password. So for user nayeem the password will benayeem123, rubi123 for user rubi and so on.

Create another bash file as follows:

#!/bin/sh
for i in `more userlist.txt `
do
echo $i
echo $i"123" | passwd –-stdin "$i"
echo; echo "User $username’s password changed!"
done

Run the file. All the passwords are changed.

If you want to force all your users to change password, use the following code:

Force all your users to change their passwords because the temporary password is a security risk

#!/bin/sh
for i in `more userlist.txt `
do
echo $i
echo $i | change -d 0 "$i"
echo; echo "User $i will be forced to change password on next login!"
done

I then log as that user and see this

WARNING: Your password has expired.
You must change your password now and login again!
Changing password for user amcorona.
Changing password for amcorona
(current) UNIX password:

RoundCube installed great – easy and straight forward. Here is the error I received:

IMAP Error: Authentication for steveoh@thelambdas.com failed (LOGIN): “a001 NO Authentication failed.”

Warning: Cannot modify header information – headers already sent in /var/www/webmail/program/include/rcmail.php on line 951

There is very little to no solutions out there.  So I had to play with the configuration file and each argument, one by one (file: main.inc.php in the config directory).

Leave the username_domain field blank.  My server, apparently, doesn’t require the full email address, only the user name, for authentication.

From:
$rcmail_config['username_domain'] = ‘example.com’;

To:
$rcmail_config['username_domain'] = ”;

This solved the problem, and I’m able to log in using ONLY the user name (ie. username, not username@example.com).

Good luck.