Mar  9 00:24:16 mail postfix/smtpd[3370]: NOQUEUE: reject: RCPT from mail.provider.com[1.2.3.4]: 450 4.1.1 <alias@example.com>: Recipient address rejected: unverified address: host my.mail.server[private/dovecot-lmtp] said: 550 5.1.1 <alias@example.com> User doesn't exist: alias@example.com (in reply to RCPT TO command); from=<sender@provider.com> to=<alias@example.com> proto=ESMTP helo=<mail.provider.com>

auth: Info: ldap(webmaster@apfel-q.de): unknown user

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
allow_percent_hack = no
append_dot_mydomain = no
compatibility_level = 2
inet_interfaces = all
inet_protocols = all
mydestination = $myhostname, localhost.mail.server, localhost
myhostname = my.mail.server
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
myorigin = /etc/mailname
readme_directory = no
recipient_delimiter = +
smtpd_sasl_auth_enable = yes
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous, noplaintext
smtpd_sasl_tls_security_options = noanonymous
smtpd_sasl_type = dovecot
smtpd_sender_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_non_fqdn_sender, reject_unknown_sender_domain, reject_unauth_pipelining
swap_bangpath = no
virtual_alias_maps = ldap:/etc/postfix/ldap/virtual-alias-maps.cf
virtual_mailbox_domains = ldap:/etc/postfix/ldap/virtual-mailbox-domains.cf
virtual_mailbox_maps = ldap:/etc/postfix/ldap/virtual-mailbox-maps.cf
virtual_transport = lmtp:unix:private/dovecot-lmtp

postmap -q "alias@example.com" ldap:/etc/postfix/ldap/virtual-alias-maps.cf