Unable to send mail to [domain information was removed by Moderator]

Dears,

I have just activated a trial period for my company. Everything is working fine, except that I cannot delivery mails to my new email account: [email account information was removed by Moderator] from external other addresses (Hotmail, libero.it, ...).

Is there any limitation ?

Thanks

Error message is:

<[email account information was removed by Moderator]>: host

    inboundsmtpprofile-250434-mail5.customer.frontbridge.com[157.56.249.60]

    said: 550 5.7.1 Unable to relay (in reply to RCPT TO command)