Email Quota Working but not Displaying

I've setup an account with a quota of 30MB, just to test it, once the limit is reached, fortunately, it cannot receive mail.

Using Roundcube, Mail.app, and Thunderbird, btw, it doesn't show me the quota.

Do you have any suggestion?

 

These applications are not designed to show you the quota. I don't know if there's an email client that shows you the quota.

 

That's not true...
If I use my gmail account the quota is shown correctly.

 

I don't use Gmail, but I guess they have written their own webmail client.

 

There is a quota plugin for SquirrelMail: http://www.squirrelmail.org/plugin_view.php?id=237
I guess other programs have similar add-ons.