Had a person reply by HTML email via Yahoo Mail, and their email signature was not stripped out although there was a string of hyphens. The following was posted as the reply:
Thanks, Person! Did I get everything you wanted? <b>--------------------
Mobile: +1 (222) 555-1212
Office: +1 (222) 555-1313
I have the original email headers/source available for anyone who wants to look at this bug more closely.