Easy answer.
It works for me.
USE `test`;
/*Table structure for table person */
DROP TABLE IF EXISTS person;
CREATE TABLE person (
id int(11) NOT NULL AUTO_INCREMENT,
email text CHARACTER SET utf8 COLLATE utf8_swedish_ci,
PRIMARY KEY (id),
FULLTEXT KEY email (email)
) ENGINE=MyISAM AUTO_INCREMENT=7 DEFAULT CHARSET=latin1;
/*Data for the table `person` */
insert into person(id,email) values
(1,'Fred@gmail.com')
,(2,'Wilmä@outlook.com')
,(3,'Barney@microsoft.com')
,(4,'Betty@microsoft.com')
,(5,'Pebbles@hotmail.com')
,(6,'Bammbamm@geewiz.com');
mysql> SELECT * FROM person
-> WHERE MATCH (email) AGAINST('@microsoft.com');
+----+----------------------+
| id | email |
+----+----------------------+
| 3 | Barney@microsoft.com |
| 4 | Betty@microsoft.com |
+----+----------------------+
2 rows in set (0.00 sec)
mysql>
Now you show us your table and data that doesn't work.
Good luck,
Barry.