When searching for a work item to add an email to, you may not immediately find the work item that you are looking for. Usually, this will be because the work item does not have a status that you are currently filtering by.
You can adjust what statuses you are filtering by - it's best to filter by all five.
Additionally to help you find that work item, try using a three-keyword search including:
Company name
Work type
Month, date or year
