Hey Zimbra team, I just tried to email sales@zimbra.com about purchasing Network Edition licenses and it bounced:

This is the Postfix program at host dogfood.zimbra.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to <postmaster>

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The Postfix program

<mhayes@zimbra.com>: zimbra.com