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Easy Imap + Smtp + Spam killer server - Linux

This uses Postfix for Smtpd, Dovecot for Imapd (SSL) and spamassasin / postgrey for spam filtering.

Postfix does Smtpd (with SSL if wanted)

Dovecot does Imap (with SSL), can do Pop3 if anybody still uses that

Spamassasin does it's best at detecting / flagging spam and moving it to "Junk" folder

Postgrey does greylisting, which removes a ton of spam (but add a small delay to emails delivery)

Install packages

apt-get install postfix dovecot spamassasin postgrey libsasl2-modules

Create SSl certs

cd /etc/ssl/certs/
openssl genrsa -des3 -rand /etc/hosts -out smtpd.key 1024
chmod 600 smtpd.key
openssl req -new -key smtpd.key -out smtpd.csr
openssl x509 -req -days 3650 -in smtpd.csr -signkey smtpd.key -out smtpd.crt
openssl rsa -in smtpd.key -out smtpd.key.unencrypted
mv -f smtpd.key.unencrypted ../private/smtpd.key
# what's this for? : openssl req -new -x509 -extensions v3_ca -keyout cakey.pem -out cacert.pem -days 3650

Dovecot(Imap) config

vi /etc/dovecot/dovecot.conf

# !! MAKE SURE TO COMMENT THIS OUT (protocols=none)!!
#protocols = none   
disable_plaintext_auth = no
log_timestamp = "%b %d %H:%M:%S "
log_path = /var/log/dovecot.log
ssl = yes
ssl_cert_file = /etc/ssl/certs/smtpd.crt
ssl_key_file = /etc/ssl/private/smtpd.key
# the password you set for the certificate
ssl_key_password = mycertpassword 
# mail will go in user_home/mail/
mail_location = maildir:~/mail 
mail_access_groups = mail
auth_username_chars = abcdefghijklmnopqrstuvwxy
protocol imap {
  imap_client_workarounds = delay-newmail tb-extra-mailbox-sep
# Note: Idle interval here helps with push to mobile (2mn default = phone battery drain)
  imap_idle_notify_interval = 24 mins
}
auth default {
  mechanisms = plain login
  passdb pam {
  }
  userdb passwd {
  }
  socket listen {
    client {
      path = /var/spool/postfix/private/auth
      user = postfix
      group = postfix
      mode = 0660
    }
  }
}

Postfix config

vi /etc/postfix/master.cf

smtp      inet  n       -       n       -       -       smtpd -o content_filter=spamassassin
smtps     inet  n       -       n       -       -       smtpd -o content_filter=spamassassin
pickup    fifo  n       -       n       60      1       pickup
cleanup   unix  n       -       n       -       0       cleanup
qmgr      fifo  n       -       n       300     1       qmgr
#qmgr     fifo  n       -       n       300     1       oqmgr
tlsmgr    unix  -       -       n       1000?   1       tlsmgr
rewrite   unix  -       -       n       -       -       trivial-rewrite
bounce    unix  -       -       n       -       0       bounce
defer     unix  -       -       n       -       0       bounce
trace     unix  -       -       n       -       0       bounce
verify    unix  -       -       n       -       1       verify
flush     unix  n       -       n       1000?   0       flush
proxymap  unix  -       -       n       -       -       proxymap
proxywrite unix -       -       n       -       1       proxymap
smtp      unix  -       -       n       -       -       smtp
relay     unix  -       -       n       -       -       smtp
        -o smtp_fallback_relay=
showq     unix  n       -       n       -       -       showq
error     unix  -       -       n       -       -       error
retry     unix  -       -       n       -       -       error
discard   unix  -       -       n       -       -       discard
local     unix  -       n       n       -       -       local
virtual   unix  -       n       n       -       -       virtual
lmtp      unix  -       -       n       -       -       lmtp
anvil     unix  -       -       n       -       1       anvil
scache    unix  -       -       n       -       1       scache

# Use spamassasin
spamassassin unix -     n       n       -       -       pipe
  user=spamd argv=/usr/bin/spamc -f -e
        /usr/sbin/sendmail -oi -f MISSING_VALUE ! MISSING_VALUE !

vi /etc/postfix/main.cf

daemon_directory = /usr/lib/postfix

smtpd_banner = $myhostname ESMTP $mail_name
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
delay_warning_time = 4h

myhostname = mail.mycomp.net
mydomain = mycomp.net
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = mycomp.net
mydestination = localhost, localhost.localdomain, mail.mycomp.net mycomp.net

mynetworks = 127.0.0.1

mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = -
inet_interfaces = all

smtpd_use_tls = yes
smtpd_tls_loglevel = 2
smtpd_tls_cert_file = /etc/ssl/certs/smtpd.crt
smtpd_tls_key_file = /etc/ssl/private/smtpd.key
smtpd_sasl_auth_enable = yes
smtpd_client_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination
smtpd_sender_restrictions = permit_sasl_authenticated, permit_mynetworks
smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination, check_policy_service inet:127.0.0.1:10023
broken_sasl_auth_clients = yes
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous

Postgrey config

vi /etc/default/postgrey

# 1mn delay
POSTGREY_OPTS="--inet=10023 --delay=60"

Spamassasin config

Left it "stock"

Restarting and checking

/etc/init.d/spamassasin restart
/etc/init.d/postgrey restart
/etc/init.d/postfix restart
/etc/init.d/dovecot restart

Then Tail the logs and try Imap / SMTP and make sure there are no errors:

tail -f /var/log/dovecot.log /var/log/mail.err /var/log/mail.log

Last modified: Wed Apr 27 12:51:19 EDT 2011 by

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