Deprecated and Headed for the Dustbin
By now, you have probably heard that some PHP features, while convenient, can also cause PHP security problems. This article discusses one of those, called register_globals. It is a thing you do not want. …
Many old projects have bad code, but the budget doesn't exist to rewrite the codebase. You can update this code to be safer by introducing contemporary input validation, sanitation, and safer database queries.
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions.
Consider email address RFCs:
Look at HTML5 form input element (with type=email) regex pattern: