Whats the maximun limit of email addresses i can put in the bcc line (Outlook 2003 SP2 with Exch 200



I am using Outlook 2003 SP2 with Exchange 2003 SP2. Whats the maximum number of emails I can put into BCC. We have 45000 members and often needed to send emails to them. When more than 1000 emails are copied and pasted from excel into BCC, all are not copied into BCC rather stopped at less than 1000. Any changes can be made on Outlook or Exchange to resolve this.