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There are some ways to validate an email via PHP. See an example of how to validate an email via PHP with the help of preg_match regular expression.
Learn about how to create a Mailto forms with examples. See also the advantages that Mailto forms can have.
Learn about how to create a Mailto link in HTML step by step with examples. See also the downsides that Mailto links can have.
PHP mail is the built in PHP function that is used to send emails from PHP scripts. See an example of how to send mail via PHP.