How to know my mail is successfully send

[Anon]

Hello,

Currently I am working on a project to send email by my PHP pgm. It works seems ok, except some email address. However, if I put a wrong / invalid to the receiver address (To) field and use PHP mail() function to send the email. The return code is still 1. Is there anyway I can know that my mail is really successfully send?

Thanks,
Raymond

[Anon]

Unfortunately, internet mail is an unreliable delivery system.
There is no end-to-end confirmation of message delivery.
However, you often are informed of failed delivery, so you
can improve your chances of hearing about it by making sure
that your return address is a valid address that you do look
at from time to time.