Probleam with outgoing Emails if it 's morethan 50 nos

[Nagella]

Hi,
I have DSL internet connection at my work place,I am facing probleam regarding outgoing emails.
I am using MS outlook2000 mailing service.
I am able to sent less than 50 Email address without any probleam whereas if it is morethan 50 outlook is unable to forward Emails to Receipients,it was saying error message as follows:

The message could not be sent because one of the recipients was rejected by the server. Server Response: '550 Too many recipients' (Account: 'adin@compro-group.com', SMTP server: 'compro-group.com', Error Number: 0x800ccc79)


I would appreciate for great help.

Thanks
Nagella