What the Red Means

The lines that the user needs to enter or customize will be in red in this tutorial!
The rest should mostly be copy-and-pastable.

About PHP mail()

The PHP mail() function uses the program in sendmail_path configuration directive to send emails. This is set up as sendmail by default.
While most Linux installations have sendmail preinstalled, there is always a hassle of setting up SPF/PTR records, generating DKIM keys and a lot more to ensure that the email sent by your PHP script is not flagged as spam. A SMTP client called MSMTP can be used to send emails using third-party SMTP servers, this can also be used by PHP’s mail() in the place of sendmail.

Installation

To install MSMTP on Fedora Linux use yum:

yum install msmtp

CentOS repository doesn’t have a RPM package for MSMTP so we need to install it from source:

yum install make gcc pkgconfig
wget http://sourceforge.net/projects/msmtp/files/msmtp/1.4.31/msmtp-1.4.31.tar.bz2/download
tar -xvf msmtp-1.4.31.tar.bz2
cd msmtp-1.4.31
./configure
make
make install

The latest version is 1.4.31 at the time of this writing but it may change in future so to get the latest version, visit this sourceforge page.
On Ubuntu/Debian distribution use apt-get:

apt-get install msmtp

Arch Linux users:

sudo pacman -S msmtp

Configuring MSMTP

The configuration file of MSMTP is stored in ~/.msmtprc for each user and /etc/msmtprc is the
system wide configuration file.
Open the configuration file in your directory.

vi ~/.msmtprc

Add the following lines for a Yahoo account:

account yahoo
tls on
tls_starttls off
tls_certcheck off
auth on
host smtp.mail.yahoo.com
user user1
from user1@yahoo.com
password yourYahooPa5sw0rd

For Gmail, use the following settings:

account gmail
tls on
tls_certcheck off
auth on
host smtp.gmail.com
port 587
user user1@gmail.com
from user1@gmail.com
password yourgmailPassw0rd

This file can also have more than one account, just ensure that the “account” value is unique for each section.
Save the file and use chmod to make this file readable only by the owner since it contains passwords.
This step is mandatory because msmtp won’t run if the permissions are more than 600.

chmod 600 ~/.msmtprc

Before implementing this in PHP, check from the command-line to ensure it works properly. To do this, create a plain text file containing a simple email:

echo -e "From: alice@example.com n
To: bob@domain.com n
Subject: Hello World n
n
This email was sent using MSMTP via Gmail/Yahoo." >> sample_email.txt

Now send this email:

cat sample_email.txt | msmtp --debug -a gmail bob@domain.com

Replace the word “gmail” with “yahoo” or whatever you entered for the “account” option. You’ll see a lot of messages because of the
“–debug” parameter. This is to make troubleshooting easy if things don’t work as expected.
If bob@domain.com receives this email, everything is setup correctly so copy this file to the /etc directory:

cp -p ~/.msmtprc /etc/.msmtp_php

Change the ownership to the username under which the web server is running. This can be “apache”, “www-data”, or “nobody” depending on the Linux distribution on your VPS and web server installed:

chown www-data:www-data /etc/.msmtp_php

Configuring PHP

Open the php.ini file, its location varies according to the OS and PHP type installed (PHP CGI, mod_php, PHP-FPM etc):

vi /etc/php5/php.ini

Find the following line:

sendmail_path =

Modify it by adding the path to the msmtp command:

sendmail_path = "/usr/bin/msmtp -C /etc/.msmtp_php --logfile /var/log/msmtp.log -a gmail -t"

Manually create a log file and change its ownership to the username your web server is running as:

touch /var/log/msmtp.log
chown www-data:www-data /var/log/msmtp.log

Restart your web server to apply the changes:

service httpd restart

In Arch Linux, this is done using the systemctl command:

systemctl restart httpd

Depending on your OS and web server, replace “httpd” with the appropriate name. If PHP is running as a separate process (like PHP-FPM), restart it instead:

service php5-fpm restart

Create a PHP script with a simple mail() to test this setup:

<?php
if(mail("receipient@domain.com","A Subject Here","Hi there,nThis email was sent using PHP's mail function."))
print "Email successfully sent";
else
print "An error occured";
?>

Access this file from the web browser.

http://www.example.com/file.php

If this email wasn’t sent you can check the msmtp log file for errors.

tail /var/log/msmtp.log

Common errors

If the email was not sent when using the PHP script, troubleshoot as follows:

Check if you edited the correct php.ini file. This can be confirmed by creating a phpinfo(); file and checking the “Loaded Configuration File” section.
The path to the msmtp configuration file might be wrong or the web server doesn’t have permission to read this file.
Check if an email is sent by running the script using command-line PHP:

php /var/www/html/file.php