but mail () function generates the following error: Warning: mail () [function.mail]: SMTP server response: 451
means that: 451 - The command has-been aborted due to a server error.
so I would like to know how to use gmail smtp server if possible.
My message was very clear, I tried with the smtp of my ISP (topnet) but it did not work because it seems to me that the mail () function does not work for
this server (SMTP server response: 451), so I wanted to know what it is possible to use the SMTP server for gmail, and I just found out now that it's possible but after some configuration, this is the Solution: