When I try to send to MySQL a srting whith a @ it says me:
You have an error in your SQL syntax; check the manual that corresponds to your
MySQL server version for the right syntax to use near '@hotmail.com)' at line 2
What code are you using that it inserts email into the database?
Are you properly escaping the input value or using prepared statements? If not, you may just be exploiting an SQL Injection Attack vulnerability in your website by accident.