See if the box is checked and size too small if it is:
To send large messages
Many e-mail and news servers limit the size of the messages you can receive and send. Usually this limit is one megabyte (1 MB) per message, including all attached files.
With Outlook Express, you can send large messages or files to e-mail and news servers that have size limits, by breaking the messages into smaller ones. When the group of messages is received, the e-mail program combines them into one message.
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.
This may also be related to your problem:
To combine multipart messages
Sometimes, when a large message (one that contains pictures, audio files, or other large objects) is sent in e-mail or posted to a newsgroup, it is broken into smaller files and displayed as several messages. You can combine the messages to recreate the original message and display it in Outlook Express.
Select all of the messages that are part of the original message (each part will usually have a number).
On the Message menu, click Combine and Decode.
If needed, reorder the parts in the correct sequence.
After you combine and decode the message, it is displayed in a separate window. The message will continue to be displayed in the message list as several smaller messages. To save the recreated message, on the File menu, click Save As.
Edited by Major Payne, 21 January 2008 - 10:25 AM.