If you are using Outlook Express you can break up large messages into smaller ones. When the group of messages is received, the mail program recombines them into one message. Usually this limit is one megabyte (1 MB) per message, including all attached files.
To send large messages
On the Tools menu, click Accounts.
On either the Mail or News tab, click Properties.
On the Advanced tab, select the Break apart messages larger than x KB check box and then enter the maximum file size the server will allow.
That's pretty much it.