Configure Office 365 Email on Linux using Postfix

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

Wondering to send alerts from the 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:

# For Redhat based 
 sudo yum install postfix cyrus-sasl-plain mailx -y

# For Debian Based
sudo apt 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 protected]:PASSWORD

Step 3 — Configure Multiple Emails [Optional]

if you need multiple emails add them like below

vim /etc/postfix/sasl_passwd

[smtp.office365.com]:587 [email protected]:PASSWORD
[smtp.office365.com]:587 [email protected]:PASSWORD
[smtp.office365.com]:587 [email protected]: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 protected]                         [smtp.office365.com]:587
[email protected]                            [email protected]
[email protected]                            [email protected]

Step 5— map the files to postfix

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

$ postmap  main.cf
$ postmap  sasl_passwd
$ postmap  sender_relay

Step 6— Send Email

To send Email, run like below command.

$ echo  "This is the Test Email" | mailx -r "[email protected]"  -s "This test mail 98" [email protected]

Step 6 — Check Logs [Optional]

For debugging log file is 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" [email protected] < file.txt

Sending the 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 protected], [email protected] < file.txt

Adding Attachments

$ mailx - s "Test Mail by mailx" [email protected] -a File.txt

Adding CC & BCC

$ mail - s "A mail sent using mailx" [email protected] -c [email protected] -b [email protected]

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