Um noch eine SMTP Auth anzubieten um seine Clients beim Versenden zu authentifieren müssen folgende Dateien so verändert werden:

main.cf

myhostname = mail.hostname.com
myorigin = /etc/mailname

alias_maps = $alias_database
virtual_mailbox_domains         = hash:/etc/postfix/virtual_domains

virtual_mailbox_base            = /srv/vmail

virtual_alias_maps              = hash:/etc/postfix/virtual_maps
#virtual_minimum_uid             = 101

virtual_uid_maps                = static:5000
virtual_gid_maps                = static:5000

virtual_transport               = dovecot

virtual_mailbox_limit = 10240000

# dovecot_destination_recipient_limit = 1

mydestination = localhost
mynetworks = 127.0.0.0/8

smtpd_banner = $myhostname ESMTP Mailserver
home_mailbox = mails/

# Zertifikate für SMTP
smtpd_tls_cert_file = /etc/postfix/mail.cert
smtpd_tls_key_file = /etc/postfix/mail.key

# SMTP Einstellungen
smtpd_use_tls = yes
#tpd_enforce_tls = no
smtpd_tls_auth_only = no

# SALS Auth für Dovecot
smtpd_sasl_auth_enable = yes
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_local_domain =
smtp_sasl_auth_enable = no
broken_sasl_auth_clients = yes

# Mailbox Einstellungen
mailbox_size_limit = 512000000
message_size_limit = 104857600


# Antispam Confis
smtpd_helo_required = yes
smtpd_helo_restrictions = reject_invalid_hostname

smtpd_recipient_restrictions = permit_mynetworks, reject_unknown_recipient_domain, permit_sasl_authenticated, reject_unauth_destination

smtpd_sender_restrictions = reject_unknown_address

smtpd_client_restrictions = reject_invalid_hostname

strict_rfc821_envelopes = yes

Diese Zeile in der master.cf

smtp    inet    n       -       n       -       -       smtpd

dovecot.conf

base_dir = /var/run/dovecot/
# log_path = /var/log/dovecot.log
protocols = imap
ssl_disable = no
verbose_proctitle = yes
#first_valid_uid = 3000
#last_valid_uid = 3000
#first_valid_gid = 8
#last_valid_gid = 8
#valid_chroot_dirs = /var/mail
mail_location = maildir:~/Maildir
maildir_copy_with_hardlinks = yes

disable_plaintext_auth = yes

protocol imap {
}

# auth_verbose = yes

auth default {
        socket listen {

        client {
                path = /var/spool/postfix/private/auth
                mode = 0660
                user = postfix
                group = postfix
            }

        master {
            path = /var/run/dovecot/auth-master
            mode = 0600
            user = vmail
            group = vmail
            }

        }
        mechanisms = plain

        passdb passwd-file {
            args = /etc/dovecot/dovecot.passwd
        }
        passdb pam {
        }
        userdb static {
          args = uid=vmail gid=vmail home=/srv/vmail/%u
        }

}

protocol lda {
        postmaster_address = postmaster@hostname.com
}