?????? ??: Sendmail?postfix?????? ????IP????IDC??? ???

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???????? Sendmail?postfix??????????IP????IDC??
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Contents

• Email relative RFC
• Postfix compare with Sendmail
• Mail deliverly process
• Mail relay process
• DNS MX Resource Record
• MX Backup
• Postfix definitive
• Postfix Major MDA purpose
• Postfix Big picture
• Postfix Queue Manager
• Postfix Content Filter
• Postfix Configuration
• Sendmail definitive
• Sendmail Major MDA purpose
• Sendmail Big picture
• Sendmail Configuration
• Different between Postfix Sendmail Command
• Different between Postfix Sendmail
  Configuration

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Email relative RFC

• RFC 2181
• Clarifications to the DNS Specification
• RFC 2821
• communicate with SMTP protocol for
  exchange mails
• RFC 1939
• retrieve mails with POP3 protocol
• RFC 2060
• retrieve mails with IMAP protocol

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MUA/MTA/MDA

• MUA (Mail User Agent)
• Outlook , Thunderbird , Eudora , pine
• MTA (Mail Transfer Agent)
• Postfix , Qmail , Sendmail , MS Exchange
• MDA (Mail Delivery Agent)
• local , smtp , sendmail , virtual , lmtp

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Postfix compare with Sendmail

• Reliability prevent resource exhaust
• Queue Management flush/hold /re-queue
• Modules dozen of MDAs
• Configuration Setting separate parameter
• Concurrency Control outgoing/incoming flow
• Transport designate MDA
• Privilege chroot
• Blocking Client restriction/Syntex/
• Content check/User defined

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Mail deliverly process
Sender mico_at_aptg.net
Mail Storage
MUA
MDA
Mail System
SMTP
Recipient quasar_at_aptg.net
MTA
SMTP
MTA
POP/IMAP
MUA
DNS
Domain aptg.net
POP3 / IMAP
Yellow ? MDA Green ? MUA Red ? Storage pink ?
Server
Mail from mico_at_aptg.net Mail to
quasar_at_aptg.net
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Mail relay process
Sender tony_at_aptg.net
MUA
MDA
MTA
Mail System
Recipient quasar_at_pchome.com.tw
SMTP
DNS
MTA
MUA
Domain aptg.net
Mail from tony_at_aptg.net Mail to
quasar_at_pchome.com.tw
Yellow ? MDA Green? MUA Pink ? Server
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DNS MX Resource Record
pchome.com.tw MX preference10 mail
exchangermx.pchome.com.tw
mx.pchome.com.tw Address 211.20.188.150
DNS Query Response ( Step 2,3,4,5)
Resolver
SMTP (step 7)
Client Outlook
aptg.net
mx.pchome.com.tw (211.20.188.150)
SMTP (step 1,6)

• From tony_at_aptg.net To
  quasar_at_pchome.com.tw
• Step 1 MUA deliver mail(s) to aptg.net for relay
• Step 2 aptg.net request pchome.com.tw for DNS
  MX RR by Resolver
• Step 3 PCHOME DNS server respond MX RR
  mx.pchome.com.tw
• Step 4 Resolver request for A RR of MX RR
• Step 5 PCHOME DNS server respond A RR
  211.20.188.150
• Step 6 Resolver provide pchome mail server IP to
  aptg.net
• Step 7 aptg.net deliver mail(s) to
  211.20.188.150 Port 25 with SMTP protocol

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MX Backup
Internet
MX RR
SMTP
Mail1.a.b.c
Deliver process
DNS Server
SMTP
SMTP
Queue
Mail2.a.b.c
SMTP
mail.a.b.c MX preference 10, mail
exchanger mail1.a.b.c mail.a.b.c MX
preference 20, mail exchanger mail2.a.b.c
Yellow ? MDA Pink ? Server
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Postfix definitive

• Postfix Major MDA purpose
• Postfix Big picture
• Postfix Queue Manager
• Postfix Content Filter
• Postfix Configuration

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Postfix Major MDA purpose

• master initiate/restart MDA , concurrency
  limitation
• qmgr decide transport, move/flush/delete/hold
  queue
• cleanup assign QueueID, push to qmgr (incoming)
• smtpd listenning incoming request
• pickup get queue from maildrop
• rewrite rewrite header
• smtp handle outgoing request
• local put mail into disk (local user
  maildir/mailbox format)
• lmtp put mail into disk (local/virtual user
  other format)
• virtual put mail into disk (virtual user
  maildir/mailbox format)
• pipe pipe to program
• bounce handle return mail

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Postfix Big Picture (1/7)
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Postfix Big Picture (2/7)From outside and relay
to outside domain
qmgr
SMTP Server / MUA send mail(s) to outside domain
incoming
active
smtp
smtpd
cleanup
DNS Server
Yellow ? MDA Blue ? Queue Pool Gray ? Queue
Manager Pink ? Server
Trivial- rewrite
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Postfix Big Picture (3/7)From outside and
deliver to local domain
Mail Storage
SMTP Server / MUA deliver mail(s) to inside domain
qmgr
incoming
active
local/lmtp/ virtual
Aliases/forward table
smtpd
cleanup
apol-idc_at_aptg.com.tw quasar_at_aptg.com.tw tony_at_a
ptg.com.tw luc_at_aptg.com.tw
Yellow ? MDA Blue ? Queue Pool Gray ? Queue
Manager Pink ? Storage
Trivial- rewrite
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Postfix Big Picture (4/7)From local host and
relay to outside domain
From local host
postdrop
qmgr
incoming
maildrop
active
smtp
Pickup
cleanup
DNS Server
Yellow ? MDA Blue ? Queue Pool Gray ? Queue
Manager Pink ? Server
Trivial- rewrite
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Postfix Big Picture (5/7)From local host and
deliver to local domain
From local host
Mail Storage
postdrop
qmgr
incoming
maildrop
active
local/lmtp/ virtual
Aliases/forward table
Pickup
cleanup
apol-idc_at_aptg.com.tw quasar_at_aptg.com.tw tony_at_a
ptg.com.tw luc_at_aptg.com.tw
Yellow ? MDA Blue ? Queue Pool Gray ? Queue
Manager Red ? Storage
Trivial- rewrite
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Postfix Big Picture (6/7)MDA qmgr
OUTPUT MDA
INPUT MDA
qmgr
active
maildrop
smtp
postdrop
local
hold
deferred
smtpd
virtual
incoming
pipe
pickup
cleanup
lmtp
trivial- rewrite
Internal MDA
Yellow ? MDA Blue ? Queue Pool Gray ? Queue
Manager
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Postfix Big Picture (7/7)Adding Content-Filter
qmgr
Port25
smtpd
incoming
active
cleanup
deferred
cleanup
chkmsg smtp
smtpd
Yellow ? MDA Blue ? Queue Pool Gray ? Queue
Manager Deep Blue ? Amavis
Port10025
Port10024
Amavis
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Postfix ConfigurationMaster.cf
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Postfix Configuration - main.cf (1/3)
Filter
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Postfix Configuration - main.cf (2/3)
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Postfix Configuration - main.cf (3/3)
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Sendmail definitive

• Sendmail Major MDA purpose
• Sendmail Big picture
• Sendmail Configuration

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Sendmail Major MDA purpose

• smtp handle outgoing request
• local put mail into disk (local user mailbox
  format)
• pipe to program
• uucp unix to unix copy
• X.400 other address format

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Sendmail Big Picture
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Sendmail Configuration sendmail.cf (1/3)
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Sendmail Configuration sendmail.cf (2/3)
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Sendmail Configuration sendmail.cf (3/3)
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Different between Postfix Sendmail Command

• start/stop/reload Daemon
• postfix start/stop/reload
• sendmail bd q1h/killall TERM
  sendmail/killall HUP sendmail
• flush/delete/requeue queue
• postfix flush/postsuper d
  ALL/postsuper r
• sendmail q/ rm queue / none
• major configuration file
• master.cf / main.cf
• sendmail.cf / sendmail.mc /
  local-host-names

Postfix
Sendmail
Postfix
Sendmail
Postfix
Sendmail
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Different betweenPostfix Sendmail
Configuration (1/3)

• major configuration file
• master.cf / main.cf
• sendmail.cf / sendmail.mc /
  local-host-names
• Local domain
• mydestination aptg.net
  (main.cf)
• Cwaptg.net (sendmail.cf?local-host-
  names)
• Relay domain
• relay_host apol.com.tw (main.cf)
• apol.com.tw (relay-domains)

Postfix
Sendmail
Postfix
Sendmail
Postfix
Sendmail
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Different betweenPostfix Sendmail
Configuration (2/3)

• Smart relay
• transport_maps
  hash/etc/postfix/transport (main.cf)
• apol.com.tw smtpmx.apol.com.tw25
  (/etc/postfix/transport)
• DSsmtp.aptg.net (sendmail.cf)
• Queue Bounce
• maximal_queue_lifetime 1d
  (main.cf)
• O Timeout.queuereturn1d
  (sendmail.cf)
• Queue retry
• queue_run_delay 4h (main.cf)
• O Timeout.queuewarn4h
  (sendmail.cf)

Postfix
Sendmail
Postfix
Sendmail
Postfix
Sendmail
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Different betweenPostfix Sendmail
Configuration (3/3)

• Process Control
• 
  (master.cf)
• service type private unpriv chroot
  wakeup maxproc command args
• smtp inet n -
  n - 300 smtpd
• O MaxDaemonChildren300
  (sendmail.cf)
• Max Message Size
• message_size_limit 10240000
  (main.cf)
• O MaxMessageSize 10240000
  (sendmail.cf)
• Recipients limitation
• smtpd_recipient_limit 100
  (main.cf)
• O MaxRecipientsPerMessage100
  (sendmail.cf)

Postfix
Sendmail
Postfix
Sendmail
Postfix
Sendmail
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Reference

• Postfix Official site
• http//www.postfix.org
• Sendmail Official site
• http//www.sendmail.org
• V-Bird Postfix Building
• http//linux.vbird.org/linux_server/0390postfix.p
  hp
• V-Bird Sendmail Building
• http//linux.vbird.org/linux_server/0380sendmail.
  php
• Sendmail Instruction
• http//fanqiang.chinaunix.net/a6/b3/index_b.html
• Postfix Instruction
• http//linux.tnc.edu.tw/techdoc/postfix-howto.htm
  

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