Hi everybody!

If I try to send a mail to an external account which definitely exists, I get the error mentioned in the title. The strange thing is, that this only happens, if I try to send this mail from my zimbra account. If I send it from a gmx account for example, it works pretty well.

What could be the reason for that? I didn't change anything of the configuration on zimbra, but since yesterday clients start complaining about it.

Some weeks ago I followed the "Improving Anti-spam system" thread of the wiki and made the following restrictions:

zimbra@mail-new:/root> zmprov gacf | grep zimbraMtaRestriction
zimbraMtaRestriction: reject_invalid_hostname
zimbraMtaRestriction: reject_non_fqdn_hostname
zimbraMtaRestriction: reject_non_fqdn_sender
Further, I enabled smtpd_reject_unlisted_recipients in zmmta.cf, but this is just for incoming mails, right?

Maybe you need to know my main.cf as well:

sender_canonical_maps = ldap:/opt/zimbra/conf/ldap-scm.cf
virtual_alias_domains = ldap://opt/zimbra/conf/ldap-vad.cf
recipient_delimiter =
smtpd_tls_cert_file = /opt/zimbra/conf/smtpd.crt
smtpd_tls_auth_only = no
myhostname = mail-new.domain.com
virtual_mailbox_domains = ldap:/opt/zimbra/conf/ldap-vmd.cf
mydestination = localhost
mailbox_size_limit = 0
setgid_group = postdrop
smtpd_client_restrictions = reject_unauth_pipelining
virtual_alias_maps = ldap:/opt/zimbra/conf/ldap-vam.cf
transport_maps = ldap:/opt/zimbra/conf/ldap-transport.cf
sendmail_path = /opt/zimbra/postfix-
message_size_limit = 10240000
broken_sasl_auth_clients = yes
alias_maps = hash:/etc/aliases
manpage_directory = /opt/zimbra/postfix-
smtpd_helo_required = yes
in_flow_delay = 1s
daemon_directory = /opt/zimbra/postfix-
virtual_transport = error
mynetworks =
smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination, reject_invalid_hostname, reject_non_fqdn_hostname, reject_non_fqdn_se
nder, permit
smtpd_tls_loglevel = 3
relayhost =
disable_dns_lookups = no
content_filter = smtp-amavis:[]:10024
virtual_mailbox_maps = ldap:/opt/zimbra/conf/ldap-vmm.cf
mail_owner = postfix
version =
mailq_path = /opt/zimbra/postfix-
header_checks = pcre:/opt/zimbra/conf/postfix_header_checks
smtpd_use_tls = yes
queue_directory = /opt/zimbra/data/postfix/spool
newaliases_path = /opt/zimbra/postfix-
smtpd_reject_unlisted_recipient = yes
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_tls_key_file = /opt/zimbra/conf/smtpd.key
command_directory = /opt/zimbra/postfix-
smtpd_sasl_auth_enable = yes
If you have any idea why this error occurs, please let me know! Thank you!