OLEXP: Err Msg: "An Unknown Error Has Occurred" in Outlook Express

When you use Outlook Express 5 or later to download, combine, and decode newsgroup posts with fragmented binary attachments or multipart e-mail messages with fragmented binary attachments, the following error message may be displayed: If you click Details, the following information is displayed: NOTE: This behavior occurs if the fragmented attachment contains more than 255 parts.

This is an architectural limitation of the new message store that was introduced with Outlook Express 5 .dbx files. The .dbx files support only up to 256 simultaneous connections to the store file, which is why this process stops working after 257 message parts.

This behavior is by design.

You can use Outlook Express to fragment an attached binary file into multiple segments when you upload binary attachments to newsgroups or send binary attachments with an e-mail message.

Some Internet service providers (ISPs) and other e-mail gateways place limits on the size of binary attachments (a typical size limit for attachments is 500 KB-1 MB). If you need to upload or send an attachment that is larger than the size limit (for example, an .avi or .mpeg file), you can use this capability to fragment a binary attachment into smaller pieces that fit through the gateway, and then recombine the pieces on the other end.

To fragment binary attachments in Outlook Express:

1. On the Tools menu, click Accounts.
2. Click the account you want to configure, click Properties, and then click Advanced.
3. In the Posting area (if you are modifying a newsgroup account) or the Sending area (if you are modifying an e-mail account), click to select the break apart messages larger than check box.
4. In the Edit box, type a number that is greater than 16 KB (the default size is 60 KB), and then click OK.

To recombine fragmented messages or newsgroup posts:

1. Press and hold down the SHIFT key while clicking all parts of the message. You can identify the parts of the message by the parenthetical notation of (x/y) in the subject line, where y is the total number of messages and x is the offset identifier of that fragment. For example:
   messagetitle (1/3)
   messagetitle (2/3)
   messagetitle (3/3)
2. Right-click one of the messages, and then click Combine and Decode.
3. When the Order for Decoding dialog box is displayed, verify that the fragments are in the correct order and that all fragments are present in the list (you can use the Move Up and Move Down buttons if one or more fragments are out of the correct order).
4. Click OK.

For additional information, please click the article number below to view the article in the Microsoft Knowledge Base: