Problems with Outlook/Outlook Express

[skirmish]

Hi, i currently have an ISPCP RC4 working and i have problems to send mail with Outlook or Outlook Express... (may be with any other MS Client.. weird, no?)...

The problem is in the postfix policy, this reject any email that i send, almost if i check to authenticate first...

Error in OE:
The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was 'XXXXX@gmail.com'. Subject 'test', Account: 'ispCP', Server: 'mail.blahblah.com', Protocol: SMTP, Server Response: '504 5.5.2 <mythril>: Helo command rejected: need fully-qualified hostname', Port: 25, Secure(SSL): No, Server Error: 504, Error Number: 0x800CCC79

any idea?? i have the default configuration of ispcp-postfix

p.d.: sorry for my english...