Dank dir.
Ich habe mich anhand der Doku und der hier im wiki verlinkten Artikel durchgearbeitet und es scheint alles so zu funktionieren, wie ich mir das vorstelle. Ich kopiere hier mal meine main.cf und master.cf rein. Zum einen findet es evtl. jemand hilfreich, der was ähnliches vorhat und zum anderen findet sich evtl. jemand, der mal drüber gucken kann. Evtl. sagt ihr ja: "Bist du verrückt? So kannst du doch keinen Mailserver betreiben." In diesem Fall wäre ich für Hinweise sehr dankbar.
main.cf
###
# Allgemein
###
smtpd_banner = $myhostname ESMTP $mail_name
biff = no
append_dot_mydomain = no
readme_directory = no
compatibility_level = 2
myhostname = email.meineDomain.de
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = $myhostname, email.meineDomain.de, localhost.meineDomain.de, , localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
smtpd_sender_login_maps = hash:/etc/postfix/controlled_envelope_senders
###
# TLS parameters
###
tls_preempt_cipherlist = yes
tls_ssl_options = NO_COMPRESSION
tls_high_cipherlist = EDH+CAMELLIA:EDH+aRSA:EECDH+aRSA+AESGCM:EECDH+aRSA+SHA256:EECDH:+CAMELLIA128:+AES128:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!DSS:!RC4:!SEED:!IDEA:!ECDSA:kEDH:CAMELLIA128-SHA:AES128-SHA
#ausgehende SMTP-Verbindungen
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtp_tls_security_level = dane
smtp_dns_support_level = dnssec
smtp_tls_protocols = !SSLv2, !SSLv3
smtp_tls_ciphers = high
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
#eingehende SMTP-Verbindungen
smtpd_tls_security_level = may
smtpd_tls_protocols = !SSLv2, !SSLv3
smtpd_tls_ciphers = high
smtpd_tls_cert_file=/etc/letsencrypt/live/email.meineDomain.de/fullchain.pem
smtpd_tls_key_file=/etc/letsencrypt/live/email.meineDomain.de/privkey.pem
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
###
#Restrictions
###
smtpd_relay_restrictions = reject_non_fqdn_recipient reject_unknown_recipient_domain permit_mynetworks reject_unauth_destination
smtpd_client_restrictions = permit_mynetworks reject_unknown_client_hostname
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks reject_invalid_helo_hostname reject_non_fqdn_helo_hostname reject_unknown_helo_hostname
smtpd_data_restrictions = reject_unauth_pipelining
mua_relay_restrictions = reject_non_fqdn_recipient,reject_unknown_recipient_domain,permit_mynetworks,permit_sasl_authenticated,reject
mua_sender_restrictions = permit_mynetworks,reject_non_fqdn_sender,reject_sender_login_mismatch,permit_sasl_authenticated,reject
mua_client_restrictions = permit_mynetworks,permit_sasl_authenticated,reject
###
#korrekten absender setzen
###
smtp_sender_dependent_authentication = yes
smtp_sasl_auth_enable = yes
smtp_sasl_security_options = noplaintext noanonymous
smtp_sasl_tls_security_options = noanonymous
smtp_connection_cache_on_demand = no
smtp_sasl_password_maps = hash:/etc/postfix/sasl_password
sender_dependent_relayhost_maps = hash:/etc/postfix/sender_dependentmaster.cf
#
# Postfix master process configuration file. For details on the format
# of the file, see the master(5) manual page (command: "man 5 master" or
# on-line: http://www.postfix.org/master.5.html).
#
# Do not forget to execute "postfix reload" after editing this file.
#
# ==========================================================================
# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (no) (never) (100)
# ==========================================================================
smtp inet n - y - - smtpd
-o smtpd_sasl_auth_enable=no
#smtp inet n - y - 1 postscreen
#smtpd pass - - y - - smtpd
#dnsblog unix - - y - 0 dnsblog
#tlsproxy unix - - y - 0 tlsproxy
submission inet n - y - - smtpd
-o syslog_name=postfix/submission
-o smtpd_tls_security_level=encrypt
-o smtpd_sasl_auth_enable=yes
-o smtpd_sasl_path=smtpd
-o smtpd_sasl_security_options=noanonymous
-o smtpd_tls_auth_only=yes
-o broken_sasl_auth_clients=yes
# -o smtpd_reject_unlisted_recipient=no
-o smtpd_client_restrictions=$mua_client_restrictions
# -o smtpd_helo_restrictions=$mua_helo_restrictions
-o smtpd_sender_restrictions=$mua_sender_restrictions
# -o smtpd_recipient_restrictions=
# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
-o smtpd_relay_restrictions=$mua_relay_restrictions
# -o milter_macro_daemon_name=ORIGINATING
#smtps inet n - y - - smtpd
# -o syslog_name=postfix/smtps
# -o smtpd_tls_wrappermode=yes
# -o smtpd_sasl_auth_enable=yes
# -o smtpd_reject_unlisted_recipient=no
# -o smtpd_client_restrictions=$mua_client_restrictions
# -o smtpd_helo_restrictions=$mua_helo_restrictions
# -o smtpd_sender_restrictions=$mua_sender_restrictions
# -o smtpd_recipient_restrictions=
# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING
#628 inet n - y - - qmqpd
pickup unix n - y 60 1 pickup
cleanup unix n - y - 0 cleanup
qmgr unix n - n 300 1 qmgr
#qmgr unix n - n 300 1 oqmgr
tlsmgr unix - - y 1000? 1 tlsmgr
rewrite unix - - y - - trivial-rewrite
bounce unix - - y - 0 bounce
defer unix - - y - 0 bounce
trace unix - - y - 0 bounce
verify unix - - y - 1 verify
flush unix n - y 1000? 0 flush
proxymap unix - - n - - proxymap
proxywrite unix - - n - 1 proxymap
smtp unix - - y - - smtp
relay unix - - y - - smtp
-o syslog_name=postfix/$service_name
# -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq unix n - y - - showq
error unix - - y - - error
retry unix - - y - - error
discard unix - - y - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - y - - lmtp
anvil unix - - y - 1 anvil
scache unix - - y - 1 scache
postlog unix-dgram n - n - 1 postlogd
#
# ====================================================================
# Interfaces to non-Postfix software. Be sure to examine the manual
# pages of the non-Postfix software to find out what options it wants.
#
# Many of the following services use the Postfix pipe(8) delivery
# agent. See the pipe(8) man page for information about ${recipient}
# and other message envelope options.
# ====================================================================
#
# maildrop. See the Postfix MAILDROP_README file for details.
# Also specify in main.cf: maildrop_destination_recipient_limit=1
#
maildrop unix - n n - - pipe
flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
#
# ====================================================================
#
# Recent Cyrus versions can use the existing "lmtp" master.cf entry.
#
# Specify in cyrus.conf:
# lmtp cmd="lmtpd -a" listen="localhost:lmtp" proto=tcp4
#
# Specify in main.cf one or more of the following:
# mailbox_transport = lmtp:inet:localhost
# virtual_transport = lmtp:inet:localhost
#
# ====================================================================
#
# Cyrus 2.1.5 (Amos Gouaux)
# Also specify in main.cf: cyrus_destination_recipient_limit=1
#
#cyrus unix - n n - - pipe
# user=cyrus argv=/cyrus/bin/deliver -e -r ${sender} -m ${extension} ${user}
#
# ====================================================================
# Old example of delivery via Cyrus.
#
#old-cyrus unix - n n - - pipe
# flags=R user=cyrus argv=/cyrus/bin/deliver -e -m ${extension} ${user}
#
# ====================================================================
#
# See the Postfix UUCP_README file for configuration details.
#
uucp unix - n n - - pipe
flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
#
# Other external delivery methods.
#
ifmail unix - n n - - pipe
flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp unix - n n - - pipe
flags=Fq. user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix - n n - 2 pipe
flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension}
mailman unix - n n - - pipe
flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
${nexthop} ${user}P.S. Nochmal um klarzustellen, was der Server tun soll. Der Server soll ausschließlich eMails von meinen Mailclients entgegen nehmen und über die korrekten/zuständigen Mailserver weiter verschicken. Eigentlich dürfte der nie eine eingehende eMail zu Gesicht bekommen. Er ist auch in den DNS Einträgen für keine Domain als Mailserver verantwortlich oder so. (lediglich eMails an benutzer@email.meineDomain.de würden hier ankommen und wegen der aliases direkt weitergeleitet.)
P.P.S. Was genau an dem hier Wiki Eintrag SASL-Authentifizierung-als-Server falsch ist, habe ich jetzt nicht erkannt. Ich habe mich durchaus daran orientiert und es scheint ja zu funktionieren. Das verunsichert mich natürlich etwas. Hoffe ich habe dadurch keine Sicherheitslücken geöffnet.
