I'm just not sure whether the problem rests with the transport or alias_maps and alias_database -- alias_maps points to an empty file.
Pardon the repost of similar data. Here's a slightly edited version, minor correction in naming conventions:
root@dur:~#
root@dur:~# grep alias /etc/postfix/main.cf
alias_maps = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases
alias_database = hash:/var/lib/mailman/data/aliases
#alias_database = hash:/etc/aliases
root@dur:~#
root@dur:~# postmap -v /etc/postfix/transport
postmap: name_mask: all
postmap: inet_addr_local: configured 2 IPv4 addresses
postmap: inet_addr_local: configured 2 IPv6 addresses
postmap: open hash /etc/postfix/transport
postmap: Compiled against Berkeley DB: 5.1.25?
postmap: Run-time linked against Berkeley DB: 5.1.25?
root@dur:~#
root@dur:~# cat /etc/postfix/transport
lists.dur.bounceme.net mailman:
root@dur:~#
root@dur:~# cat /var/lib/mailman/data/aliases
root@dur:~#
root@dur:~# ll /var/lib/mailman/data/
total 44
drwxrwsr-x 2 root list 4096 Aug 28 08:48 ./
drwxrwsr-x 8 root list 4096 Aug 27 19:58 ../
-rw-r--r-- 1 root list 0 Aug 28 04:36 aliases
-rw-r--r-- 1 root list 12288 Aug 28 04:36 aliases.db
-rw-r----- 1 root list 41 Aug 27 21:04 creator.pw
-rw-rw-r-- 1 root list 10 Aug 27 19:58 last_mailman_version
-rw-r--r-- 1 root list 14100 Oct 19 2011 sitelist.cfg
root@dur:~#
root@dur:~# ll /etc/aliases
-rw-r--r-- 1 root list 1852 Aug 27 21:18 /etc/aliases
root@dur:~#
root@dur:~# cat /etc/aliases
usenet: root
## mailman mailing list
mailman: "|/var/lib/mailman/mail/mailman post mailman"
mailman-admin: "|/var/lib/mailman/mail/mailman admin mailman"
mailman-bounces: "|/var/lib/mailman/mail/mailman bounces mailman"
mailman-confirm: "|/var/lib/mailman/mail/mailman confirm mailman"
mailman-join: "|/var/lib/mailman/mail/mailman join mailman"
mailman-leave: "|/var/lib/mailman/mail/mailman leave mailman"
mailman-owner: "|/var/lib/mailman/mail/mailman owner mailman"
mailman-request: "|/var/lib/mailman/mail/mailman request mailman"
mailman-subscribe: "|/var/lib/mailman/mail/mailman subscribe mailman" mailman-unsubscribe: "|/var/lib/mailman/mail/mailman unsubscribe mailman"
## gmane.mail.mailman.user.1 mailing list
gmane.mail.mailman.user.1: "|/var/lib/mailman/mail/mailman post gmane.mail.mailman.user.1" gmane.mail.mailman.user.1-admin: "|/var/lib/mailman/mail/mailman admin gmane.mail.mailman.user.1" gmane.mail.mailman.user.1-bounces: "|/var/lib/mailman/mail/mailman bounces gmane.mail.mailman.user.1" gmane.mail.mailman.user.1-confirm: "|/var/lib/mailman/mail/mailman confirm gmane.mail.mailman.user.1" gmane.mail.mailman.user.1-join: "|/var/lib/mailman/mail/mailman join gmane.mail.mailman.user.1" gmane.mail.mailman.user.1-leave: "|/var/lib/mailman/mail/mailman leave gmane.mail.mailman.user.1" gmane.mail.mailman.user.1-owner: "|/var/lib/mailman/mail/mailman owner gmane.mail.mailman.user.1" gmane.mail.mailman.user.1-request: "|/var/lib/mailman/mail/mailman request gmane.mail.mailman.user.1" gmane.mail.mailman.user.1-subscribe: "|/var/lib/mailman/mail/mailman subscribe gmane.mail.mailman.user.1" gmane.mail.mailman.user.1-unsubscribe: "|/var/lib/mailman/mail/mailman unsubscribe gmane.mail.mailman.user.1"
root@dur:~#
root@dur:~# grep mailman /etc/postfix/master.cf
mailman unix - n n - - pipe
flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
root@dur:~#
root@dur:~# newaliases
root@dur:~#
root@dur:~# postfix stop;postfix start
postfix/postfix-script: stopping the Postfix mail system
postfix/postfix-script: starting the Postfix mail system
root@dur:~#
root@dur:~# tail /var/log/mail.log
Aug 28 08:58:28 dur postfix/master[13190]: terminating on signal 15
Aug 28 08:58:28 dur postfix/postfix-script[13304]: starting the Postfix mail system Aug 28 08:58:28 dur postfix/master[13305]: daemon started -- version 2.9.1, configuration /etc/postfix Aug 28 08:58:29 dur postfix/postfix-script[13314]: stopping the Postfix mail system Aug 28 08:58:29 dur postfix/master[13305]: terminating on signal 15 Aug 28 08:58:30 dur postfix/postfix-script[13419]: starting the Postfix mail system Aug 28 08:58:30 dur postfix/master[13420]: daemon started -- version 2.9.1, configuration /etc/postfix Aug 28 08:59:09 dur postfix/smtpd[13435]: connect from localhost[127.0.0.1] Aug 28 08:59:10 dur postfix/smtpd[13435]: NOQUEUE: reject: RCPT from localhost[127.0.0.1]: 550 5.1.1 <test6@dur.bounceme.net>: Recipient address rejected: User unknown in local recipient table; from=<thufir@dur.bounceme.net> to=<test6@dur.bounceme.net> proto=ESMTP helo=<dur.bounceme.net> Aug 28 08:59:13 dur postfix/smtpd[13435]: disconnect from localhost[127.0.0.1] root@dur:~# root@dur:~# root@dur:~# postconf -n alias_database = hash:/var/lib/mailman/data/aliases alias_maps = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases append_dot_mydomain = no biff = no broken_sasl_auth_clients = yes config_directory = /etc/postfix default_transport = smtp home_mailbox = Maildir/ inet_interfaces = loopback-only mailbox_command = /usr/lib/dovecot/deliver -c /etc/dovecot/conf.d/01-mail-stack-delivery.conf -m "${EXTENSION}" mailbox_size_limit = 0 mailman_destination_recipient_limit = 1 mydestination = $myhostname localhost.$mydomain localhost $mydomain myhostname = dur.bounceme.net mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 readme_directory = no recipient_delimiter = + relay_domains = lists.example.com relay_transport = relay relayhost = smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache smtp_use_tls = yes smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu) smtpd_recipient_restrictions = reject_unknown_sender_domain, reject_unknown_recipient_domain, reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination smtpd_sasl_auth_enable = yes smtpd_sasl_authenticated_header = yes smtpd_sasl_local_domain = $myhostname smtpd_sasl_path = private/dovecot-auth smtpd_sasl_security_options = noanonymous smtpd_sasl_type = dovecot smtpd_tls_auth_only = yes smtpd_tls_cert_file = /etc/ssl/certs/ssl-mail.pem smtpd_tls_key_file = /etc/ssl/private/ssl-mail.key smtpd_tls_mandatory_ciphers = medium smtpd_tls_mandatory_protocols = SSLv3, TLSv1 smtpd_tls_received_header = yes smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtpd_use_tls = yes tls_random_source = dev:/dev/urandom transport_maps = hash:/etc/postfix/transport root@dur:~#