Can anyone help with this little problem...

At my desk i will work my way through emails: deleting them as required, however when i go to my blackberry the emails i have deleted are still on there (unopened or opened), so at times i find myself with some 50 or so unopened emails on the handset, all of which i have actually opened, and the majority of which i may have deleted.

Can someone help and tell me which of the setting i have incorrect and tell me how to resolve this.

i want anything i delete on my desktop to be deleted on my blackberry.

thanks,

a.