Directadmin – Unrouteable address error on incoming mail

I had this stupid error the other day on Directadmin. I upgraded Exim to the latest version and then all mail sent to which was on this server was bounced with the error “Unrouteable address”. From the past, I knew that errors like this can be due to exceeded mail limit. But in this case, this was happening only for one mail out of 50 others, and no limits were reached.

After some searching, I found out that there was an alias pointing to the email address itself, which was causing this error. I removed the forwarder (alias) and incoming mail started to work again on this mailbox.

2021-05-09 20:53:28 H=([]) [] F=<> rejected RCPT <>: Unrouteable address

So I had mail forwarder like: ->

So when dealing with such an error, just remove the alias like described above.

Directadmin – install Drush locally – drush: command not found

This is how you can install Drush locally and make drush command localy on specific user.

  • First go to root directory of user and login with this user
    [root@da ~]# cd /home/mydrush/
    [root@da mydrush]# su mydrush
  • Install drush via composer
    [mydrush@da mydrush]$ composer require drush/drush
    Using version ^10.4 for drush/drush
    ./composer.json has been created
    Running composer update drush/drush
    Loading composer repositories with package information
    Updating dependencies
  • Create alias to drush for this user. Open file .bashrc and add line bellow to it and save. Then run source.
    # User specific environment and startup programs
    export PATH="$HOME/vendor/bin:$PATH"
    [mydrush@da mydrush]$ source .bashrc
  • This is it
    [mydrush@da mydrush]$ drush version
    Drush version : 10.4.3

Special thanks to Adrian

Slow email sending from cPanel SMTP

I received a few complaints from different people, that sending of email messages is really slow. This didn’t make any sense, because no modifications were made on the server.

After an hour, I found that this was caused by Exim setting “Delay SMTP Transaction”. Quoting cPanel: The SMTP receiver will wait a few additional seconds for a connection when it detects spam messages in order to reduce inbound spam. 

So it’s another weapon to fight spam mail, but it makes sending slower.

You can disable this feature in Exim Configuration Manager -> ACL Options -> Introduce a delay into the SMTP transaction for unknown hosts and messages detected as spam.

When disabled, your emails should be fast again.

Directadmin – auto assign custom authorized_keys for newly created users – SSH access

I setup a Directadmin server which was primary for website hosting. Separating every project with new DirectAdmin user is a good practice security vise. If one website/project is hacked, other sites that are with different users are safe. But creating new users and then set up ssh keys that are allowed for every user can be time consumedly. In this case, ssh public keys were the same for every user as only developers were able to ssh connect to user account. I created a simple script that will create .ssh directory and authorized_keys with public keys for every user.

  • First, create script inside /usr/local/directadmin/scripts/custom/.
  • Create template file with all ssh  public keys that should be assign to every new user. I created file /usr/local/directadmin/data/custom-authorized_keys
  • Add this content to the script:

    mkdir /home/$username/.ssh
    chown $username:$username /home/$username/.ssh
    cp /usr/local/directadmin/data/custom-authorized_keys /home/$username/.ssh/authorized_keys
    chown $username:$username /home/$username/.ssh/authorized_keys
    chmod 600 /home/$username/.ssh/authorized_keys

    echo "SSH keys added!"

    exit 0;
  • Give this script execution rights
    chmod +x /usr/local/directadmin/scripts/custom/

That is it. Every time a new user is created, .ssh directory with authorized_keys will be created inside user’s home account.

Limit number of email recipients with Roundcube

I had an issue with one of the mail servers on which one user’s account password was stolen and was sending spam. Spam was sent from Roundcube and there was a very large number of recipients in one email. Limit the number of recipients in Postfix was not an option. It had to be done on webmail. It is very simple with Roundcube. Just add variable bellow in your Roundcube configuration file –

$config['max_recipients'] = 10;

This will allow only 10 recipients in one email message. Of course you can change the number according to your needs.

Cpanel – migrate all email accounts to new cPanel server with existing passwords. No password change

For migration of user accounts between cPanel servers, there is a superb “Transfer tool” which is provided and is part of Cpanel. With it, you can simply migrate all data from one server to another. But what about when you have the same accounts on both servers and you don’t want to overwrite data on a new server? I had one account for which the only email was necessary to transfer. This is not something transfer tool can do because I didn’t want to overwrite account.

If you have many email accounts and you don’t know passwords for them, it is realy pain in  the ass to change all passwords and make transfer via imapsync. But luckily, you can simly copy all email accounts from one Cpanel server to another by copy user’s “passwd” and “shadow” file.

Here is how you can migrate all email accounts from one server to another without changing username/password. All passwords will be transferred.

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Directadmin – get disk size information for every email account on your server/user

If you want to get information about how much of disk is consuming every email account on your Directadmin server, then you can use this command.

[root@post ~]# find /home/*/imap/*/*/ -maxdepth 1 -type d -exec du -sh {} \; | awk -F '/' {'print $6"@"$5 " -> " $1'} -> 60K -> 60K -> 529M -> 529M -> 772K

If you would want for every email account of some specific user, than you can use this:

[root@post ~]# find /home/user1/imap/*/*/ -maxdepth 1 -type d -exec du -sh {} \; | awk -F '/' {'print $6"@"$5 " -> " $1'} -> 1.3G -> 1.3G -> 68M

Simple, but it can save some time 🙂

Build NGINX with GeoIP2 support from source

I used GeoIP library with Nginx for quite some time, but it came to EOL. GeoIP2 is now avalible. It is great tool for blocking unwanted traffic from your webserver. This was done on Centos 7. If you don’t want to pay for getpagespeed’s payed version, than you must build this module from source.

First, you’ll need to know your curent NGINX version

[root@myserver ~]# nginx -v
nginx version: nginx/1.16.1

Then, download exact same version of NGINX from this site and unpack it. In my case:

[root@myserver ~]# wget
[root@myserver ~]# tar -xvzf nginx-1.16.1.tar.gz
[root@myserver ~]# cd nginx-1.16.1.tar.gz

Then you should download ngx_http_geoip2_module – geoip2 module for NGINX:

[root@myserver ~]# wget
[root@myserver ~]# unzip

You should install GCC and Development Tools for dependencies.

[root@myserver ~]# yum groupinstall ‘Development Tools’
[root@myserver ~]# yum install gcc

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Make single Roundcube instance use multi different databases

I had to configure webmail service with Roundcube which would allow connecting multi mail servers o one platform. Every mail server had it’s own Roundcube instance already, but idea was, that only one installation can handle all mail servers.

I found out, that this can be done pretty symple with some php in roundcube configuration.

Open your roundcube configuration file, for example:

vi /var/www/roundcube/config/

Fetch correct hostname for specific webmail instance in php variable.

$host = $_SERVER['SERVER_NAME'];

Then you should create switch statement that will be able to manage correct database connection and host for specific server name – mail service. You can also have different types of database. For example mysql and postgres.

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Fix high server load and memory/cpu consumption of clamd ( ClamAV )

I had troubles with one of Directadmin servers which was constantly loading because clamd process. When executing top command, clamd was always top on the list. As I researched, there is no way you can limit ClamAV’s memory and CPU consumption via its configuration itself. This is how you do it.

What you have to do is limit clamd within startup script, so that clamd will start with some limitations.

Just open ClamAV startup script. I this case CentOS 7:

vi /etc/systemd/system/clamd.service

Then add this lines. Of course change according to your needs.

IOSchedulingPriority = 7
CPUSchedulingPolicy = 5
Nice = 19

Your startup script should now look something like this:

Description = Generic clamav scanner daemon
After =

Type = simple
ExecStartPre=-/bin/mkdir -p /var/run/clamd
ExecStartPre=-/bin/chown -R clamav:clamav /var/run/clamd
ExecStart = /usr/local/sbin/clamd --foreground=yes
Restart = on-failure
PrivateTmp = true
IOSchedulingPriority = 7
CPUSchedulingPolicy = 5
Nice = 19

WantedBy =

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