Note_Tech

All technological notes.

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Project - Sending Gmail using postfix on Redhat8

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• Project - Sending Gmail using postfix on Redhat8
  • Install Package
  • Add Gmail Credential
    • Create Credential File
    • Convert the credential file into db file
    • Change permission and ownership of the credential file
  • Postfix Configuration
    • Backup configuration file
    • Configure
    • Start Postfix service
  • Test by sending email

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Install Package

su - root

# install package
yum install -y postfix mailx

# # verify
rpm -qa | grep postfix
rpm -qa | grep mailx

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Add Gmail Credential

Create Credential File

vi /etc/postfix/sasl/sasl_passwd

• Add credential

[smtp.gmail.com]:587 email@gmail.com:password

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Convert the credential file into db file

postmap /etc/postfix/sasl/sasl_passwd
ll /etc/postfix/sasl
# -rw-r--r--. 1 root root    58 Nov 22 00:20 sasl_passwd
# -rw-r--r--. 1 root root 12288 Nov 22 00:22 sasl_passwd.db

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Change permission and ownership of the credential file

• Change permission

# change ownership
chown root:root /etc/postfix/sasl/sasl_passwd

# limited only the root user can read and write the credential file
chmod 600 /etc/postfix/sasl/*
ll /etc/postfix/sasl/*
# -rw-------. 1 root root    58 Nov 22 00:20 /etc/postfix/sasl/sasl_passwd
# -rw-------. 1 root root 12288 Nov 22 00:22 /etc/postfix/sasl/sasl_passwd.db

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Postfix Configuration

Backup configuration file

• Backup /etc/postfix/main.cf

cp /etc/postfix/main.cf /etc/postfix/main.cf_bkp

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Configure

vi /etc/postfix/main.cf

# configure relay host
relayhost = [smtp.gmail.com]:587

# configure hostname
myhostname = rhelhost.localdomain

# specify location of sasl_passwd file
smtp_sasl_password_maps = hash:/etc/postfix/sasl/sasl_passwd

# Enable SASL authentication for postfix
smtp_sasl_auth_enable = yes
smtp_tls_security_level = encrypt

# Prevent anonymous authentication
smtp_sasl_security_options = noanonymous

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Start Postfix service

systemctl enable postfix.service
systemctl start postfix.service
systemctl status postfix.service

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Test by sending email

• Send email

echo "Test Mail" | mail -s "Postfix Test" target@gmail

• Send email with attachment

# create a text file
vi /home/rheladmin/note.txt
# Hello world

echo "Test Mail" | mail -s "Postfix Test" -a /home/rheladmin/note.txt target@gmail

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• Automatically send email

vi /etc/cron.hourly/auto-email

# * * * * * echo "Test Auto Email." | mail -s "Test Auto Email - $(date)" target@gmail

crontab -l /etc/cron.hourly/auto-email

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