Can't receive emails postfix/dovecot and other doubts

[eidosmatrix]

Hi people, I'm new in the community. I installed a CentOS 5.6 with ISPConfig3 following the Perfect Setup Guide. I'm having some troubles and doubts.

1st: I setted up the email service w/postfix+dovecot and I can receive mails from localhost in all domains (I configured more than 1 domains). So in the main domain (that have dns created in goddady like ns1.mydomain.com) I can receive mail from outside (gmail by example) but can't receive from outside in my others domains (ex. mydomain2.com). Any idea? I'm supecting of dns zones.
Should I create a dns zone for each domain with records like:
Zone 1: mail.mydomain.com
Zone 2: mail.mydomain3.com
Zone 3: [...] ?
Or just a main zone with my primary domain?

2nd: When I setup a new site I select Auto-Subdomain: www for catch both option (with and whitout www prefix)but nothing... www. doesn't work. I'm pretty lost at this point.

3rd: I buyed a VPS and I don't have a traditional fstab (just none / none defaults) and off course quota not work... at least installed like the guide way. How do you manage HD quotas?

Ok... too much for now.
I 'll appreciate some help!

Regards.

[falko]

Please check if your MX records point to the correct server. You can check that like this:

dig mx yourdomain.com

2nd: When I setup a new site I select Auto-Subdomain: www for catch both option (with and whitout www prefix)but nothing... www. doesn't work. I'm pretty lost at this point.

Do DNS records exist for www, and do they point to the correct server?