Re: #HY000Host 'XXX' is not allowed to connect to this MySQL server

[girionis chrysaorides]

You simply need to do:

mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
-> ON <dbname>.*
-> TO <username>@<host name>
-> IDENTIFIED BY '<password>';

where <dbname> is the name of the database you are tyring to connect to, <username> is the username of the user trying to connect to the database, <host name> the name of the host (in your case the XXX host) and <password> the password of the user.