No. Zimbra Standard or Professional licenses cannot be installed on an existing Zimbra Open Source server. The Zimbra Open Source must be upgraded to the Zimbra Network Edition software. All mailboxes, directory and data is preserved during the upgrade.
Yes, you can purchase mixed licenses of any combination. The minimum purchase units is 25 mailboxes for each type of license.
Yes, you can purchase a Zimbra license subscription for 1, 2 or 3 years. You can also purchase a perpetual license for Zimbra which is significantly cheaper should you plan on using Zimbra for 2+ years.
Yes, you can easily upgrade from Zimbra Open Source to Zimbra Standard or Professional Edition. Downgrades from Zimbra Standard or Professional to Zimbra Open Source work too!
The Zimbra Perpetual license is a nontransferable right to use the license for the number of mailboxes in the agreement. At the end of the 1st year from the date of issuance of the Zimbra license key and provided that support is still generally available, customer can pay a maintenance fee to continue to receive support, upgrades and updates or can continue to use the then current version for the number of license mailboxes in perpetuity for no additional fees.
If you need additional Zimbra mailbox licenses then you just submit an order for the number of additional licenses required in units of 25 mailboxes. The minimum order quantity is 25 mailboxes.
Agilemail will process the order and then you will be issued with an updated Zimbra license. This new license includes existing plus the additional licenses.
Fees are not prorated, instead any difference in fees are discounted against the next license renewal.
Zimbra is licensed either on an yearly subscription (1, 2 or 3 years options available) or a perpetual license with annual support. The cost for renewing the yearly subscription is the same as the initial subscription cost. There is no renewal for a perpetual license, instead you can choose to renew the annual support to continue to access Zimbra support and newer versions of Zimbra software.
15 for Zimbra Starter Edition; 25 for all other Zimbra Editions. Note: You can get 10 free licenses for the Zimbra Appliance Edition as a special offer from Zimbra.
Zimbra Professional Edition includes support for Microsoft Outlook.
Zimbra Standard Edition or Zimbra Professional Edition provide Windows Mobile phone integration.