i have a problem configuring the zimbra-server to send emails from our local server to the internet with the same domain (for example @company.com)


i can send and recieve email between our local accounts and any external provider (user1@company.com <---> userX@hotmail.com for example)
i can receive emails from external over the internet in the same domain (userExternal@company.com ---> CompanyMailProvider ---> [fetchmail to internal Server] ---> userInternal@company.com)
i can send email between 2 local accounts (user1@company.com <----> user2@company.com)

what i can't is to send mails from internal accounts to external accounts in the same domain via Internet ( userInternal@company.com --X--> CompanyMailProvider ---> userExternal@company.com)

what do i need to configure that our server only handles all our internal emails locally?? and sends all other email (even with same domain) to our CompanyMailProvire (here: 1und1.de)??

greetings, waintdeir