mapi problem

hi all,

need ur help urgently. i have designed an application that uses mapi. the emails are being sent ok without issues. The problem i am facing is that i have to send about 1500 plus emails from within my application. after sending about 400 the system prompts and error message telling that the personal address book is being used by more than one application and so i will have to close some applications to send email. There is no other application that uses outlook at that point of time. it is just my application that uses it and i cannot send bulk emails(meaning that i cannot put multiple ids in the to list or cc list ) i have to send them one by one since depending on the status different people get different emails from the application. Please help !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!