I am having trouble deleting Outllok 2011 emails, some just don’t delete

A few messages received each day, simply don't want to be deleted.  I hit delete but it just goes to the next message and the original message remains.  Most of these are junk mail types, which won't move to junk mail either.  Some of these are emails captured by my web host as either incorrectly addressed and redirected to my email account.  Any suggestions would be appreciated.