Guten Morgen,
ein Kunde meldet mir, dass der POP-3-connector von Exchange Emails nicht abholen kann, da im Header der E-Mail - ein non-delivery-report - ein Fehler im Return-Path sei. Dort befindet sich <mailer-daemon>, was Echchange als unbekannte Adresse abweist. Der Kunde meint, der Return-Path müsse leer sein oder eine gültige Mailadresse beeinhalten.
Hier ein Beispiel:
[INDENT]Return-Path: <MAILER-DAEMON>
X-Original-To: admin@example.dom
Delivered-To: admin@example.dom
Received: by mailserverdomain.mail (Postfix)
	id 4032A2684B85; Mon,  2 May 2016 09:22:26 +0200 (CEST)
Date: Mon,  2 May 2016 09:22:26 +0200 (CEST)
From: MAILER-DAEMON@mailserverdomain.mail (Mail Delivery System)
Subject: Undelivered Mail Returned to Sender
To: admin@example.dom[/INDENT]
Nach 2 Stunden google und Lektüre des Postfix-Manuals bin ich noch kein Stück weiter. Wie kann ich erreichen, dass statt "Return-Path: <MAILER-DAEMON>" "Return-Path: <MAILER-DAEMON@mailserverdomain.mail>" eingesetzt wird bzw. "Return-Path: <>"?
main.cf:
#  _    _          ___           __ _     (R)
# | |  (_)_ _____ / __|___ _ _  / _(_)__ _
# | |__| \ V / -_) (__/ _ \ ' \|  _| / _` |
# |____|_|\_/\___|\___\___/_||_|_| |_\__, |
#                                    |___/
# Copyright (c) 2009-2016 Keppler IT GmbH.
# ----------------------------------------------------------------------------
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
authorized_flush_users = root, $mail_owner
authorized_mailq_users = root, $mail_owner
biff = no
broken_sasl_auth_clients = yes
disable_vrfy_command = yes
dovecot_destination_recipient_limit = 1
inet_protocols = all
mailbox_size_limit = 0
message_size_limit = 53477376
milter_default_action = accept
mydestination = localhost.localdomain, localhost, $myhostname
myhostname = mailserverdomain.mail
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
myorigin = /etc/mailname
readme_directory = no
recipient_delimiter = +
relayhost = 
sender_bcc_maps = hash:/etc/postfix/sender_bcc
show_user_unknown_table_name = no
smtp_bind_address = xxx.xxx.xxx.xxx
smtp_bind_address6 = xxxx.xxxx.xxxx.xxxx.xxxx ....
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
smtp_tls_loglevel = 1
smtp_tls_mandatory_protocols = !SSLv2, !SSLv3
smtp_tls_protocols = !SSLv2, !SSLv3
smtp_tls_security_level = may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name
smtpd_client_restrictions =     permit_mynetworks,
    permit_sasl_authenticated,
    reject_invalid_hostname,
    reject_unknown_reverse_client_hostname,
    reject_rbl_client dul.dnsbl.sorbs.net,
    reject_rbl_client ix.dnsbl.manitu.net,
    reject_rbl_client cbl.abuseat.org,
    reject_rbl_client sbl-xbl.spamhaus.org
smtpd_discard_ehlo_keywords = silent-discard, dsn
smtpd_helo_required = yes
smtpd_helo_restrictions = reject_invalid_helo_hostname
smtpd_milters = unix:/var/run/clamav/clamav-milter.ctl, unix:/var/run/lcsam.sock
smtpd_recipient_limit = 250
smtpd_recipient_restrictions =     permit_mynetworks,
    permit_sasl_authenticated,
    reject_unauth_destination,
    reject_unknown_recipient_domain,
    check_recipient_access hash:/etc/postfix/recipient_access
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain = $mydomain
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_type = dovecot
smtpd_sender_restrictions =     permit_mynetworks,
    reject_unknown_address,
    reject_unknown_sender_domain,
    reject_non_fqdn_sender,
    check_sender_access hash:/etc/postfix/sender_access
smtpd_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
smtpd_tls_cert_file = /etc/ssl/certs/postfix.crt
smtpd_tls_ciphers = medium
smtpd_tls_dh1024_param_file = /etc/postfix/dh2048.pem
smtpd_tls_dh512_param_file = /etc/postfix/dh512.pem
smtpd_tls_exclude_ciphers = aNULL, eNULL, ADH
smtpd_tls_key_file = /etc/ssl/private/postfix.key
smtpd_tls_loglevel = 1
smtpd_tls_mandatory_ciphers = medium
smtpd_tls_mandatory_exclude_ciphers = aNULL, eNULL, ADH
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
smtpd_tls_protocols = !SSLv2, !SSLv3
smtpd_tls_security_level = may
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
virtual_alias_maps = hash:/etc/postfix/virtual_alias
virtual_gid_maps = static:8
virtual_mailbox_base = /var/mail
virtual_mailbox_domains = hash:/etc/postfix/virtual_domains
virtual_mailbox_maps = hash:/etc/postfix/virtual_alias
virtual_minimum_uid = 8
virtual_transport = dovecot
virtual_uid_maps = static:8
# <EOF>-----------------------------------------------------------------------
master.cf:
#  _    _          ___           __ _     (R)
# | |  (_)_ _____ / __|___ _ _  / _(_)__ _
# | |__| \ V / -_) (__/ _ \ ' \|  _| / _` |
# |____|_|\_/\___|\___\___/_||_|_| |_\__, |
#                                    |___/
# Copyright (c) 2009-2016 Keppler IT GmbH.
# ----------------------------------------------------------------------------
# ==========================================================================
# service type  private unpriv  chroot  wakeup  maxproc command + args
#               (yes)   (yes)   (yes)   (never) (100)
# ==========================================================================
smtp      inet  n       -       n       -       -       smtpd
submission inet n       -       n       -       -       smtpd
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
  -o smtpd_helo_required=no
  -o smtpd_helo_restrictions=
  -o smtpd_tls_dh1024_param_file=/etc/postfix/dh1024.pem
465       inet  n       -       n       -       -       smtpd
  -o smtpd_tls_wrappermode=yes
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
  -o smtpd_helo_required=no
  -o smtpd_helo_restrictions=
  -o smtpd_tls_dh1024_param_file=/etc/postfix/dh1024.pem
pickup    fifo  n       -       -       60      1       pickup
cleanup   unix  n       -       -       -       0       cleanup
qmgr      fifo  n       -       n       300     1       qmgr
tlsmgr    unix  -       -       -       1000?   1       tlsmgr
rewrite   unix  -       -       -       -       -       trivial-rewrite
bounce    unix  -       -       -       -       0       bounce
defer     unix  -       -       -       -       0       bounce
trace     unix  -       -       -       -       0       bounce
verify    unix  -       -       -       -       1       verify
flush     unix  n       -       -       1000?   0       flush
proxymap  unix  -       -       n       -       -       proxymap
proxywrite unix -       -       n       -       1       proxymap
smtp      unix  -       -       n       -       -       smtp
# When relaying mail as backup MX, disable fallback_relay to avoid MX loops
relay     unix  -       -       -       -       -       smtp
        -o smtp_fallback_relay=
#       -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq     unix  n       -       -       -       -       showq
error     unix  -       -       -       -       -       error
retry     unix  -       -       -       -       -       error
discard   unix  -       -       -       -       -       discard
local     unix  -       n       n       -       -       local
virtual   unix  -       n       n       -       -       virtual
lmtp      unix  -       -       -       -       -       lmtp
anvil     unix  -       -       -       -       1       anvil
scache    unix  -       -       -       -       1       scache
maildrop  unix  -       n       n       -       -       pipe
  flags=DROhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
dovecot   unix  -       n       n       -       -       pipe
  flags=DROhu user=mail:mail argv=/usr/lib/dovecot/deliver -f ${sender} -d ${recipient} -e
# <EOF>-----------------------------------------------------------------------
Bin für jede Hilfe dankbar.