MX (Mail Exchanger) records are DNS (Domain Name System) records that specify the mail server responsible for handling email delivery for a specific domain. In the case of Gmail, the MX record is used to direct incoming email messages to Gmail's mail servers.
Whenever someone tries to send an email to a user in your company, their SMTP server does an MX lookup in the DNS to see where to send this message. If that server is not able to find an MX record it won't be able to deliver this email.
PHP is a server-side scripting language designed for web development but also used as a general-purpose programming language.PHP is a server-side scripting language designed for web development but also used as a general-purpose programming language.
Python has a variety of libraries such as NumPy, pandas, and matplotlib that make it an ideal language for data analysis and visualization.
Java is commonly used for building enterprise-scale applications.