I have emailed Invoices to Xtracta and they are not being recognised. In the Exception file they are showing Invalid File Type.
This is because Outlook has created the attachment as the winmail.dat.
To prevent this from continuing follow the following instructions:
Click File in Outlook
Go to the Mail category
Make sure HTML or Plain Text is selected for Compose messages in this format: under Compose messages.
Now make sure Convert to HTML format or Convert to Plain Text format is selected for When sending messages in Rich Text format to Internet recipients: under Message format.
Note: if you use Outlook with an Outlook Mail on the Web (Outlook.com) account, winmail.dat attachments may be sent to people in your address book no matter your Outlook options. This is an issue with Outlook and Outlook Mail on the Web, and you will, unfortunately, need for Microsoft to update.