Sending mail with PHP Imap

I could retrieve mails from Gmail server on localhost using PHP Imap, but I could not send one. I already try 开发者_开发百科with functions imap_mail() and mail() Could you tell me how? or any thing is required such as mail server?

Thanks!

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Nearly nobody uses or supports sending mail with IMAP. Use SMTP to send mails out.

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Here is a tutorial with some helpful comments, about specifying novalidate-cert (although I agree with cweiske).