system
6
If you absolutely don’t want to get rid of it by deleting the entire content of your inbox, there’s no safe solution.
And Who is right: get yourself another mailprogram to avoid this in the future. (no means to offend you!)
There are a lot of free, safe solutions like Pegasus, iScribe, Vivian and Gemail. (the last one however only in German language)
Please do yourself a favor and abandon OutlookExpress as soon as possible 
Fast