How do I stop Bulk Mails?

I have been sending my company Bulk Mails to more than 1 thousand at one time.
Recently I upgrade my Z30 to OS 3.0 there my problems started..Now my recipients complain that they receive same duplicate more than twice. I checked and re checked before sending the mail but I always get same response. THIS ONLY STARTED AFTER I UPGRADE TO OS 3.0. I felt humiliated and shame to answer to everyone think that I made repeated mistake.

Sounds like you need an antivirus ON YOUR COMPUTER...doesn't sound like phone issue

I am using BlackBerry Z30 software release 10.3.1.522. I usually send bulk mails using Microsoft Exchange, With previous 10. 2.1 vesion i never had this problems.

You are using an OLD leak, maybe try a newer and if that still fails, then return to the version that was working fine.