Hi,

You could use a plugin to do so :

Add this hook in init() function of your plugin :

     // Hooks
     $this->add_hook('storage_connect',          array($this, 

'storage_connect'));

Then call this function :

 /**
  * Connection to IMAP server
  */
 public function storage_connect($args) {
     if ($args['driver'] == 'imap') {
         // Use an IMAP proxy ?
         if ($this->rc->config->get('use_imap_proxy', false)) {
             $args['host'] = $this->rc->config->get('imap_proxy', 

null); } } return $args; }

Add 2 new config properties : 'use_imap_proxy' => true, 'imap_proxy' => <your imap host>

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MINISTÈRES AMÉNAGEMENT DU TERRITOIRE TRANSITION ÉCOLOGIQUE

Le 13/06/2025 14:51, > nicolas.george a écrit :

Hi.

We have a mail server, let us call it clipper, and Roundcube running on a distinct server, let us call it localhost. We already have users, with their identities and their address books in the database.

I want to add imapproxy in the chain, to reduce the load on clipper. It will run on localhost.

Unfortunately, if I just write:

$config['default_host'] = 'localhost';

… then for the database the mail_host column will be localhost instead of clipper, and everybody will be considered a new user when connecting the next time.

I could do “UPDATE users SET mail_host = 'localhost' WHERE mail_host = 'clipper'” but I do not want to: for reasons of elegance and the ability to move back or to host multiple servers on the same instance, I want the database to contain the real host name.

What are the options?

I found a hack: I added “127.0.0.2 clipper” in /etc/hosts and configured imapproxy with a different FQDN for clipper. That way, Roundcube thinks it is talking to clipper when it is really talking to the proxy. And since the proxy is running on localhost I can dispense with TLS and all the security theatre of certificates.

Before thinking of this hack, I tried another one that I got halfway working: configure the firewall with a NAT chain “ip daddr $clipper tcp dport 143 counter redirect to :143”. The solution with /etc/hosts is simpler and more robust.

But these are hacks. Is there a clean supported solution?

Thanks in advance.