Sending email with PHP from an SMTP server

Question

When you are sending an e-mail through a server that requires SMTP Auth, you really need to specify it, and set the host, username and password (and maybe the port if it is not the default one - 25).

For example, I usually use PHPMailer with similar settings to this ones:

$mail = new PHPMailer();

// Settings
$mail->IsSMTP();
$mail->CharSet = 'UTF-8';

$mail->Host       = "mail.example.com";    // SMTP server example
$mail->SMTPDebug  = 0;                     // enables SMTP debug information (for testing)
$mail->SMTPAuth   = true;                  // enable SMTP authentication
$mail->Port       = 25;                    // set the SMTP port for the GMAIL server
$mail->Username   = "username";            // SMTP account username example
$mail->Password   = "password";            // SMTP account password example

// Content
$mail->isHTML(true);                       // Set email format to HTML
$mail->Subject = 'Here is the subject';
$mail->Body    = 'This is the HTML message body <b>in bold!</b>';
$mail->AltBody = 'This is the body in plain text for non-HTML mail clients';

$mail->send();

You can find more about PHPMailer here: https://github.com/PHPMailer/PHPMailer

<?php
ini_set("SMTP", "aspmx.l.google.com");
ini_set("sendmail_from", "[email protected]");

$message = "The mail message was sent with the following mail setting:\r\nSMTP = aspmx.l.google.com\r\nsmtp_port = 25\r\nsendmail_from = [email protected]";

$headers = "From: [email protected]";

mail("[email protected]", "Testing", $message, $headers);
echo "Check your email now....&lt;BR/>";
?>

or, for more details, read on.

For Unix users, mail() is actually using Sendmail command to send email. Instead of modifying the application, you can change the environment. msmtp is an SMTP client with Sendmail compatible CLI syntax which means it can be used in place of Sendmail. It only requires a small change to your php.ini.

sendmail_path = "/usr/bin/msmtp -C /path/to/your/config -t"

Then even the lowly mail() function can work with SMTP goodness. It is super useful if you're trying to connect an existing application to mail services like sendgrid or mandrill without modifying the application.

Here is a way to do it with PHP PEAR

// Pear Mail Library
require_once "Mail.php";

$from = '<[email protected]>'; //change this to your email address
$to = '<[email protected]>'; // change to address
$subject = 'Insert subject here'; // subject of mail
$body = "Hello world! this is the content of the email"; //content of mail

$headers = array(
    'From' => $from,
    'To' => $to,
    'Subject' => $subject
);

$smtp = Mail::factory('smtp', array(
        'host' => 'ssl://smtp.gmail.com',
        'port' => '465',
        'auth' => true,
        'username' => '[email protected]', //your gmail account
        'password' => 'snip' // your password
    ));

// Send the mail
$mail = $smtp->send($to, $headers, $body);

//check mail sent or not
if (PEAR::isError($mail)) {
    echo '<p>'.$mail->getMessage().'</p>';
} else {
    echo '<p>Message successfully sent!</p>';
}

If you use Gmail SMTP remember to enable SMTP in your Gmail account, under settings

EDIT: If you can't find Mail.php on debian/ubuntu you can install php-pear with

sudo apt install php-pear

Then install the mail extention:

sudo pear install mail
sudo pear install Net_SMTP
sudo pear install Auth_SASL
sudo pear install mail_mime

Then you should be able to load it by simply require_once "Mail.php" else it is located here: /usr/share/php/Mail.php

The problem is that PHP mail() function has a very limited functionality. There are several ways to send mail from PHP.

1. mail() uses SMTP server on your system. There are at least two servers you can use on Windows: hMailServer and xmail. I spent several hours configuring and getting them up. First one is simpler in my opinion. Right now, hMailServer is working on Windows 7 x64.
2. mail() uses SMTP server on remote or virtual machine with Linux. Of course, real mail service like Gmail doesn't allow direct connection without any credentials or keys. You can set up virtual machine or use one located in your LAN. Most linux distros have mail server out of the box. Configure it and have fun. I use default exim4 on Debian 7 that listens its LAN interface.
3. Mailing libraries use direct connections. Libs are easier to set up. I used SwiftMailer and it perfectly sends mail from Gmail account. I think that PHPMailer is pretty good too.

No matter what choice is your, I recommend you use some abstraction layer. You can use PHP library on your development machine running Windows and simply mail() function on production machine with Linux. Abstraction layer allows you to interchange mail drivers depending on system which your application is running on. Create abstract MyMailer class or interface with abstract send() method. Inherit two classes MyPhpMailer and MySwiftMailer. Implement send() method in appropriate ways.

There are some SMTP servers that work without authentication, but if the server requires authentication, there is no way to circumvent that.

PHP's built-in mail functions are very limited - specifying the SMTP server is possible in WIndows only. On *nix, mail() will use the OS's binaries.

If you want to send E-Mail to an arbitrary SMTP server on the net, consider using a library like SwiftMailer. That will enable you to use, for example, Google Mail's outgoing servers.

In cases where you are hosting a WordPress site on Linux and have server access, you can save some headaches by installing msmtp which allows you to send via SMTP from the standard PHP mail() function. msmtp is a simpler alternative to postfix which requires a bit more configuration.

Here are the steps:

Install msmtp

sudo apt-get install msmtp-mta ca-certificates

Create a new configuration file:

sudo nano /etc/msmtprc

...with the following configuration information:

# Set defaults.
defaults

# Enable or disable TLS/SSL encryption.
tls on
tls_starttls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt

# Set up a default account's settings.
account default
host <smtp.example.net>
port 587
auth on
user <[email protected]>
password <password>
from <[email protected]>
syslog LOG_MAIL

You need to replace the configuration data represented by everything within "<" and ">" (inclusive, remove these). For host/username/password, use your normal credentials for sending mail through your mail provider.

Tell PHP to use it

sudo nano /etc/php5/apache2/php.ini

Add this single line:

sendmail_path = /usr/bin/msmtp -t

Complete documentation can be found here:

https://marlam.de/msmtp/