This occurs only when sending messages with attachments from Outlook/Hotmail to a single domain outside of Microsoft (tonalrefraction.com).  Messages without attachments are delivered without any problems.  After reading your FAQ's it seems possible that my account may have been either compromised or spoofed.  In the meantime I have taken steps to further secure my account.  I am just an end-user and am unable to find all the information to complete your support request form.  For example I don't use telnet...