Hey Folks✌️ welcome to another post, Here we discuss about using postfix send email by command line.

Wondering to send alerts from command line to Email, here we go …

Introduction:

Postfix is a popular and widely-used open-source mail transfer agent (MTA) software. An MTA is responsible for routing and delivering email messages within a computer network, whether that network is the internet or an internal network within an organization

👇Requirements:

1. Email credentials (Microsoft 365/Gmail)

2. Linux Machine

Step 1 — Install required packages:

$ sudo yum install postfix cyrus-sasl-plain mailx -y

Step 2 — Change the main.cf:

Open the /etc/postfix/main.cf file using your favorite editor(Vim/nano/) and add the below lines:

vim /etc/postfix/main.cf

relayhost = [smtp.office365.com]:587
mynetworks = 127.0.0.0/8
inet_interfaces = loopback-only
smtp_use_tls = yes
smtp_always_send_ehlo = yes
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous
smtp_tls_security_level = encrypt
smtp_generic_maps = hash:/etc/postfix/generic
smtp_sender_dependent_authentication = yes
sender_dependent_relayhost_maps = hash:/etc/postfix/sender_relay

Step 2 — Set Password for Email:

Edit the password file /etc/postfix/sasl_passwd

For Office 365 Email-ID use like below

vim /etc/postfix/sasl_passwd

[smtp.office365.com]:587 email_1@mail.com:PASSWORD

Step 3 — Configure Multiple Emails [Optional]

if you need multiple mails add like below

vim /etc/postfix/sasl_passwd

[smtp.office365.com]:587 email_1@mail.com:PASSWORD
[smtp.office365.com]:587 email_2@mail.com:PASSWORD
[smtp.office365.com]:587 email_3@mail.com:PASSWORD

Step 4— Configure the Sender Relay [ Required only for multiple Emails]

Edit /etc/postfix/sender_relay add like below

vim /etc/postfix/sender_relay

email_1@mail.com                         [smtp.office365.com]:587
email_2@mail.com                            email_2@mail.com
email_2@mail.com                            email_2@mail.com

Step 5— map the files to postfix

Once all done, map the files into postfix. Run the below commands

$ postmap  main.cf
$ postmap  sasl_passwd
$ postmap  sender_relay

Step 6— Send Email

For send Email ,run like below command.

$ echo  "This is the Test Email" | mailx -r "sender_email@mail.com"  -s "This test mail 98" recevier_email@mail.com

Step 6 — Check Logs [Optional]

For debugging log file located on /var/log/maillog.

Open log file: tail -f /var/log/maillog

✅Mailx Usage:

• -a → add attachment

• -b → add Bcc Email

• -c → add CC Email

• -r → From Email Address

• -s → Subject of the Email

Taking the message from a file

$ mailx -s "Test Mail by mailx" person@example.com < file.txt

Sending same Mail to Multiple Recipients:

We can send the same email to multiple receivers (not by cc or bcc) as follows:

$ mailx - s "Test Mail by mailx" email_1@example.com, email_2@example.com < file.txt

Adding Attachments

$ mailx - s "Test Mail by mailx" email_1@example.com -a File.txt

Adding CC & BCC

$ mail - s "A mail sent using mailx" email_0@example.com -c email_cc@example.com -b email_bcc@example.com

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