I have one website name e.g. www.mydomain.com
Now i want to configure smtp setting in my local pc.
Below is the phpini code i have set.
Here i have not used any username and password.

[mail function]
; For Win32 only.
SMTP = mail.mydomain.com
smtp_port = 25

And it is working.. Strange !!!!
How this can work?
I mean if this is the only required info then anyone can set this detail and can use my domain's smtp.
What is the reason behind working of it?

If i want to use my gmail account info for smtp. Is it works?
what is the steps to follow?

Any help will be appreciated.

I got below error when i connect with different machine.

Warning: mail() [function.mail]: SMTP server response: 550-(TEST-PC) [xx.xx.xx.xx]:50406 is currently not permitted to relay 550-through this server. Perhaps you have not logged into the pop/imap server 550-in the last 30 minutes or do not have SMTP Authentication turned on in your 550 email client. in C:\wamp\www\email.php on line 9

I think my working pc's ip address is allowed on that mydomain.com.
How can i check on mydomain.com?

and when i use above link for sending mail from gmail account, i got below error.

SMTP -> ERROR: Failed to connect to server: Unable to find the socket transport "ssl" - did you forget to enable it when you configured PHP? (24)
SMTP Error: Could not connect to SMTP host. Mailer Error: SMTP Error: Could not connect to SMTP host.

anybody knows how to integrate gmail account information ???

Yeah Error will come, but you can find the error message on google to know the settings. Because you are not simply accessing the gmail account, there is some configuration too. So please go thru the php mailer documentation clearly to know that.