Failed to connect to mailserver at "localhost" port 25

You need to be running a mail server locally. If this is Unix, enable sendmail If this is Windows install the Simple Mail Transfer Server (not sure if the name is correct) component of IIs. E.g. for windows 2003 follow this: http://msdn.microsoft.com/en-us/library/8b83ac7t.aspx

For sending mails using php mail function is used. But mail function requires SMTP server for sending emails. we need to mention SMTP host and SMTP port in php.ini file. Upon successful configuration of SMTP server mails will be sent successfully sent through php scripts.

On windows, nearly all AMPP (Apache,MySQL,PHP,PHPmyAdmin) packages don't include a mail server (but nearly all naked linuxes do have!). So, when using PHP under windows, you need to setup a mail server!

Imo the best and most simple tool ist this: http://smtp4dev.codeplex.com/

SMTP4Dev is a simple one-file mail server tool that does collect the mails it send (so it does not really sends mail, it just keeps them for development). Perfect tool.

If you are running your application just on localhost and it is not yet live, I believe it is very difficult to send mail using this.

Once you put your application online, I believe that this problem should be automatically solved. But i think ini_set() helps you to change the values in php.ini during run time.

First of all, you aren't forced to use an SMTP on your localhost, if you change that localhost entry into the DNS name of the MTA from your ISP provider (who will let you relay mail) it will work right away, so no messing about with your own email service. Just try to use your providers SMTP servers, it will work right away.