Question about Outlook Express

I'M TRYING TO SEND A 6 PAGE NEWSLETTER TO BAOUT 80 ADDRESSES. I GOT A MESSAGE BACK THAT TELLS ME THAT MY EMAIL WASN'T SENT TO ANYONE BECAUSE IT IS TOO LONG. THE MESSAGE SAYS THAT THERE IS A LIMIT OF 12MB AND MY MSG IS 23MB. I DIDN'T KNOW THAT THERE WAS A LIMIT AND IF THERE IS CAN IT BE CHANGED AND HOW DO I GO ABOUT DOING IT. I JUST GOT ANOTHER EMAIL FROM ONE OF THE RECIPENTS WHO APPARENTLY RECIEVED THE MSG SO WHAT GIVES.