feat: add function to get email domain

src/EMail.java

@@ -14,4 +14,13 @@ public class EMail {
 		// Checks and returns if the email matches the regex pattern
 		return pattern.matcher(email).matches();
 	}
+
+	/**
+	 * Retrieves the domain part of the email address
+	 * @param email A valid email address
+	 * @return The domain of the email address from the parameter
+	 */
+	public String getDomain(String email) {
+		return email.split("@")[1];
+	}
 }