Which are the limitations of the OXtender for Plesk?
When used in flat licensing, OXtender for Plesk flat licenses are limited to up to 50 groupware accounts for Plesk 10 domains licenses, up to 150 groupware accounts for Plesk 100 domains licenses and up to 250 groupware accounts for Plesk unlimited licenses. This licensing model is available for servers having no more than 2,000 mailbox accounts in Parallels Plesk Panel. If you have more than 2,000 mailbox accounts, you must use the Open-Xchange server centric licensing. For more details please contact sales.