Thank you for tips. Unfortunatelly, none of these works.
To describe better my situation, I have a couple of accounts on zimbra server with email
zimbra_account@domain.cz. I have other acounts of domain.cz that are not on zimbra such as
nonzimbra_account@domain.cz. If I send an email from zimbra to a
nonzimbra_account@domain.cz, zimbra deals with that message as local and in log there is relay=none. I am not able to persuade zimbra to handle all the accounts as not local. I want to send everything to external smtp.domain.cz.
Thanks for any help