This is not a problem anymore. Outgoing Email Checker monitors the text of your emails as well as the Subject line and warns if you planned to include but forgot an attachment. All you need to do is to enter a list of key words that will trigger the reminder. You can select the ready-to-use template where the key words and phrases are predefined or you can modify this template. For example, the add-in can pop-up an alert when you forget to add an attachment if the email is sent to certain recipient or in case the CC or BCC line contains specific address.