My favorite Outlook add-in Forgotten Attachment Detector (FAD) from Microsoft Office Labs got updated recently.

When you send an email FAD checks the mail content against a pre-configured list of keywords that indicate you’ve forgotten to attach an attachment. If it detects this, it notifies you and gives you a chance to correct any mistakes. Simple, but life saver in some situations.

Shown below the the FAD settings screen. FAD comes with a list of phrases which imply presence of attachment with high certainty. It is comprehensive enough but you can add/remove as per your needs.

If you miss, this is the prompt you will get along with a "Show Snippet" button to see the text snippet which triggered this prompt.

You can download FAD here.