Microsoft is trying to fix a bug in the e-mail program Outlook 2010 Beta that creates unusually large e-mail files that take up too much space. The Outlook product team has offered a bug fix for both 32-bit and 64-bit systems that fixes the problem going forward, although previous e-mails will remain super-sized. This could be a problem for e-mail programs that limit message sizes, such as Gmail or BlackBerry.

The bug appears where the usage of numbered and bullet point lists in a message causes redundant cascading style sheet (CSS) definitions to be included in each outgoing message, Microsoft says. Restarting Outlook after downloading the patch removes all the extra CSS.

"If you use number and bullet lists, close Outlook at the end of each day, and your new outgoing messages will return to their normal size," wrote Jenny Liu, Outlook Program Manager, in a blog post.

To get rid of those older monster e-mails, the Outlook team suggests running Conversation Cleanup, a new feature of Outlook 2010, which moves all the older, redundant messages in the user's e-mail conversations to the Deleted Items folder. Cleanup keeps the most recent message around, Microsoft says, ensuring users have all the content in the conversation while allowing them to delete the redundant messages. And the humongous ones.

Commentors on the blog clarified that the fix is for Word 2010, not Outlook 2010, even though the bug manifests itself in Outlook. Liu also clarified in a comment that the fix is only needed for the Beta version, as future releases of it will already be fixed.