Hi to everyone's,
I run a postfix server into Debian/GNU 6.0 Linux server 2.6.32-5-amd64. The bug is that it seems run slow(from client point of view) when it send email from out of LAN where it's hosts the postfix server, that when It sended from within LAN where postfix is hosted.

I have observed, what look like a warning about of domain resolution :

Code:
May 15 13:03:35 server postfix/smtpd[17364]: warning: ??.??.??.??: hostname 110.Red-13-33-22.dynamicIP.rima-tde.net verification failed: Temporary failure in name resolution
May 15 13:03:35 server postfix/smtpd[17364]: connect from unknown[??.??.??.??]
May 15 13:03:38 server postfix/smtpd[17364]: 17448100064: client=unknown[??.??.??.??], sasl_method=PLAIN, sasl_username=email
May 15 13:03:38 server postfix/cleanup[17367]: 17448100064: message-id=<1305457557.2500.0.email>
May 15 13:03:38 server postfix/qmgr[2169]: 17448100064: from=<email>, size=532, nrcpt=1 (queue active)
May 15 13:03:38 server postfix/virtual[17368]: 17448100064: to=<email>, relay=virtual, delay=0.53, delays=0.51/0/0/0.02, dsn=2.0.0, status=sent (delivered to maildir)
May 15 13:03:38 server postfix/qmgr[2169]: 17448100064: removed
May 15 13:03:39 server postfix/smtpd[17364]: disconnect from unknown[??.??.??.??]]
I like know, if this bug could cause the delay that I perceive when email is sended ?


Code:
$> s postconf -n

biff = no
broken_sasl_auth_clients = yes
config_directory = /etc/postfix
html_directory = /usr/share/doc/postfix/html
inet_interfaces = all
local_recipient_maps = $virtual_mailbox_maps
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
mydestination = $myhostname, localhost.$myhostname, localhost
mydomain = ??????????.org
myhostname = server.??????????.org
myorigin = $mydomain
readme_directory = /usr/share/doc/postfix
recipient_delimiter = +
relayhost = ??????????.?????.org:2525
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options =
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
smtpd_sasl_local_domain = server
smtpd_sasl_path = /var/spool/postfix/private/auth
smtpd_sasl_type = dovecot
smtpd_tls_CAfile = /etc/ssl/postfix/cacert.pem
smtpd_tls_cert_file = /etc/ssl/postfix/smtpd.crt
smtpd_tls_key_file = /etc/ssl/postfix/smtpd.key
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes
virtual_alias_maps = proxy:mysql:/etc/postfix/mysql/mapas_alias_virtuales_mysql.cf
virtual_gid_maps = static:1001
virtual_mailbox_base = /var/mail/virtual
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql/mapas_dominios_virtuales_mysql.cf
virtual_mailbox_limit = 0
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql/mapas_mailbox_virtuales_mysql.cf
virtual_minimum_uid = 1001
virtual_transport = virtual
virtual_uid_maps = static:1001
Code:
$> s cat master.cf

# ==========================================================================
# service type  private unpriv  chroot  wakeup  maxproc command + args
#               (yes)   (yes)   (yes)   (never) (100)
# ==========================================================================
smtp      inet  n       -       n       -       -       smtpd
#submission inet n       -       -       -       -       smtpd
#  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject_unauth_destination
#  -o milter_macro_daemon_name=ORIGINATING
#smtps     inet  n       -       -       -       -       smtpd
#  -o smtpd_tls_wrappermode=yes
#  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
#  -o milter_macro_daemon_name=ORIGINATING
#628       inet  n       -       -       -       -       qmqpd
pickup    fifo  n       -       -       60      1       pickup
cleanup   unix  n       -       -       -       0       cleanup
qmgr      fifo  n       -       n       300     1       qmgr
#qmgr     fifo  n       -       -       300     1       oqmgr
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  -       -       -       -       -       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
#
# ====================================================================
# 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}
Best regards and thank very much.