hari ini insyaallah saya akan sedikit menceritakan langkah untuk bisa mengirim email lewan cli ubuntu (dalam kasus ini saya akan menggunakan gmail) yang nanti nya juga bisa di manfaatkan sebagai notifikasi server , berikut langkahnya :

install postfix , mailutils dan yang lain nya

root@bit-X200CA:/home/bit# apt-get install mailutils libsasl2-2 ca-certificates libsasl2-modules postfix

edit /etc/postfix/main.cf   dengan cara

root@bit-X200CA:/home/bit# pico /etc/postfix/main.cf

ubah isi main.cf  menjadi

# See /usr/share/postfix/main.cf.dist for a commented, more complete version
# Debian specific: Specifying a file name will cause the first
# line of that file to be used as the name. The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no
# appending .domain is the MUA's job.
append_dot_mydomain = no
# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h
readme_directory = no
# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.
#smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = localhost
#alias_maps = hash:/etc/aliases
#alias_database = hash:/etc/aliases
virtual_alias_maps = hash:/etc/postfix/virtual
recipient_canonical_maps = hash:/etc/postfix/recipient_canonical
mydestination = bit-X200CA, localhost.localdomain, , localhost # sesuaikan dengan pc/server anda
relayhost = smtp.gmail.com:587
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
#inet_protocols = ipv4
#myorigin = /etc/mailname
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_tls_CAfile = /etc/postfix/cacert.pem
smtp_use_tls = yes

kemudian file sasl_passwd

root@bit-X200CA:/home/bit# pico /etc/postfix/sasl_passwd

isi seperti berikut , sesuaikan passwd nya

generate sasl_passwd dengan perintah yang nntinya akan membentuk file sasl_passwd.db

postmap /etc/postfix/sasl_passwd

selanjutnya kita akan melakukan generate certificate karena kebanyakan email menggunakan koneksi TLS

root@bit-X200CA:/etc/ssl/certs# cat /etc/ssl/certs/thawte_Primary_Root_CA_-_G3.pem | tee -a /etc/postfix/cacert.pem

hasil certificate TLS yang di generate kurang lebih seperti berikut

root@bit-X200CA:/etc/ssl/certs# cat /etc/ssl/certs/thawte_Primary_Root_CA_-_G3.pem | tee -a /etc/postfix/cacert.pem
-----BEGIN CERTIFICATE-----
MIIEKjCCAxKgAwIBAgIQYAGXt0an6rS0mtZLL/eQ+zANBgkqhkiG9w0BAQsFADCB
rjELMAkGA1UEBhMCVVMxFTATBgNVBAoTDHRoYXd0ZSwgSW5jLjEoMCYGA1UECxMf
Q2VydGlmaWNhdGlvbiBTZXJ2aWNlcyBEaXZpc2lvbjE4MDYGA1UECxMvKGMpIDIw
MDggdGhhd3RlLCBJbmMuIC0gRm9yIGF1dGhvcml6ZWQgdXNlIG9ubHkxJDAiBgNV
BAMTG3RoYXd0ZSBQcmltYXJ5IFJvb3QgQ0EgLSBHMzAeFw0wODA0MDIwMDAwMDBa
Fw0zNzEyMDEyMzU5NTlaMIGuMQswCQYDVQQGEwJVUzEVMBMGA1UEChMMdGhhd3Rl
LCBJbmMuMSgwJgYDVQQLEx9DZXJ0aWZpY2F0aW9uIFNlcnZpY2VzIERpdmlzaW9u
MTgwNgYDVQQLEy8oYykgMjAwOCB0aGF3dGUsIEluYy4gLSBGb3IgYXV0aG9yaXpl
ZCB1c2Ugb25seTEkMCIGA1UEAxMbdGhhd3RlIFByaW1hcnkgUm9vdCBDQSAtIEcz
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAsr8nLPvb2FvdeHsbnndm
gcs+vHyu86YnmjSjaDFxODNi5PNxZnmxqWWjpYvVj2AtP0LMqmsywCPLLEHd5N/8
YZzic7IilRFDGF/Eth9XbAoFWCLINkw6fKXRz4aviKdEAhN0cXMKQlkC+BsUa0Lf
b1+6a4KinVvnSr0eAXLbS3ToO39/fR8EtCab4LRarEc9VbjXsCZSKAExQGbY2SS9
9irY7CFJXJv2eul/VTV+lmuNk5Mny5K76qxAwJ/C+IDPXfRa3M50hqY+bAtTyr2S
zhkGcuYMXDhpxwTWvGzOW/b3aJzcJRVIiKHpqfiYnODz1TEoYRFsZ5aNOZnLwkUk
OQIDAQABo0IwQDAPBgNVHRMBAf8EBTADAQH/MA4GA1UdDwEB/wQEAwIBBjAdBgNV
HQ4EFgQUrWyqlGCc7eT/+j4KdCtjA/e2Wb8wDQYJKoZIhvcNAQELBQADggEBABpA
2JVlrAmSicY59BDlqQ5mU1143vokkbvnRFHfxhY0Cu9qRFHqKweKA3rD6z8KLFIW
oCtDuSWQP3CpMyVtRRooOyfPqsMpQhvfO0zAMzRbQYi/aytlryjvsvXDqmbOe1bu
t8jLZ8HJnBoYuMTDSQPxYA5QzUbF83d597YV4Djbxy8ooAw/dyZ02SUS2jHaGh7c
KUGRIjxpp7sC8rZcJwOJ9Abqm+RyguOhCcHpABnTPtRwa7pxpqpYrvS76Wy274fM
m7v/OeZWYdMKp8RcTGB7BXcmer/YB1IsYvdwY9k5vG8cwnncdimvzsUsZAReiDZu
MdRAGmI0Nj81Aa6sY6A=
-----END CERTIFICATE-----

terakhir reload postfix

root@bit-X200CA:/etc/ssl/certs# /etc/init.d/postfix reload

kemudian test kirim email

root@bit-X200CA:/etc/ssl/certs# echo "test mail dari local" | mail -s "test postfix" aldykustyandi@alshifacharity.com

berikut log mail nya

root@bit-X200CA:/etc/ssl/certs# tail -f /var/log/mail.log
Jun 25 11:17:19 localhost postfix/qmgr[7368]: D526D1A0D5A: removed
Jun 25 11:18:28 localhost postfix[7415]: Postfix is running with backwards-compatible default settings
Jun 25 11:18:28 localhost postfix[7415]: See http://www.postfix.org/COMPATIBILITY_README.html for details
Jun 25 11:18:28 localhost postfix[7415]: To disable backwards compatibility use "postconf compatibility_level=2" and "postfix reload"
Jun 25 11:18:28 localhost postfix/master[6678]: reload -- version 3.1.0, configuration /etc/postfix
Jun 25 11:18:31 localhost postfix/pickup[7429]: B407F1A0D5A: uid=0 from=<root>
Jun 25 11:18:31 localhost postfix/cleanup[7448]: B407F1A0D5A: message-id=<20160625041831.B407F1A0D5A@localhost>
Jun 25 11:18:31 localhost postfix/qmgr[7430]: B407F1A0D5A: from=<root@localhost>, size=338, nrcpt=1 (queue active)
Jun 25 11:18:34 localhost postfix/smtp[7450]: B407F1A0D5A: to=<aldykustyandi@alshifacharity.com>, relay=smtp.gmail.com[74.125.200.108]:587, delay=2.8, delays=0.14/0.19/1.6/0.94, dsn=2.0.0, status=sent (250 2.0.0 OK 1466828314 h189sm3052511pfc.52 - gsmtp)
Jun 25 11:18:34 localhost postfix/qmgr[7430]: B407F1A0D5A: removed
^C

kurang lebih email nya seperti ini

selamat mencoba , dan semoga ada yang menyempurnakan  🙂 , termaksih