Installing php mail() function

Question

I have recently set up a CentOS 6.4 server using the minimalistic installation. I have a working version of PHP up and running, but I want to be able to use the mail() function in PHP.

• What do I need to make it work (mailservers, scripts, what is needed?)
• How do I proceed installing whats needed?

Answer 1

Sending E-Mails is a complicated topic, because anti-spam measurements are getting more and more aggressive. I recommend to send e-mails using SMTP and a 3rd party provider. Most of the time, you already have a way of sending and receiving emails for your project (i.e. included with your domain or webhosting). I will explain the "how" and "why" below.

How to send mails using SSMTP?

Multiple choices:

1. ssmtp.

This is a small tool that exposes a "sendmail" binary to PHP's mail() function. Install it and configure it using the /etc/ssmtp/ssmtp.conf file. Here is an example for sending mails using SSMTP and SSL:

mailhub=smtp.yourprovider.com:465
hostname=yourdomain.com
AuthUser=yourusername
AuthPass=yourpassword
FromLineOverride=NO
UseTLS=yes

When sending a mail using the mail() function, php will call the sendmail binary and ssmtp will deliver the e-mail transparently using SMTP.

2. Postfix/Exim/Sendmail

You can configure a standard mailserver for you system and configure it to relay your emails over a 3rd party provider. This is a litte more complex than ssmtp but allows accepting emails on localhost SMTP port 25. Just google for smtp relay and your mailserver name.

3. PHPMailer

When you create your own project and you can modify your code, you should use PHPMailer class, because sending an e-mail with html content, attachment or to multiple senders is complicated using the plain mail function and absolutely not recommended for beginners.

PHPMailer can send mails using SMTP itself, or it can be used together with the ssmtp tool.

Why is sending e-mails complicated?

As i said before, anti-spam measurements are getting more and more aggressive. to do it right, you have to setup a mailer daemon like postfix, exim or sendmail and configure it correctly. i.e. you need to make sure that no one can use your mailserver for sending mails without authentification. you have to configure your domain's MX record to point to your servers ip, because other mailservers verify your sender ip using the MX record. You may have to setup DKIM (DomainKeys Identified Mail) to keep you mail from being classified as Spam.

If you have setup your server and domain correctly, you are not done. The fun just starts.

If you start sending emails to different mail providers, some recipients may tag your emails as spam. This happens not only to newsletters and advertisings, some ppl are also tagging automated registration confirmations as spam. If a number of your emails got spam-tagged on a large e-mail-provider like microsoft, google or GMX they will block your IP address or classify it as spam. Then you have to sign up with microsoft and others and investigate the removal of your ip-address. This can be a time-consuming task.

it may also happen that your project gets hacked and your ip is sending millions of emails. if that happend, you may have a hard time clearing your bad ip reputation. you should have configured sending limits to limit the impact of hackers abusing you mail() function.

a 3rd party provider will do all this for you. they will configure the mailserver correctly, they will keep the ip reputation up and they will also block you from sending spam.