Default open_basedir

[omniware]

Hello.

I have some fails about squirrelmail working like http://domain.tld/webmail.
I need change the open_basedir adding

:/usr/share/squirrelmail:/etc/squirrelmail:/var/lib/squirrelmail/data:/var/lib/squirrelmail/data:/var/spool/squirrelmail/attach/

because it is mandatory to open http://domain.tld/webmail and it working fine.

Where can I adding this to put code to default at site->options->open_basedir when I add new site?

Thanks.