I ran into some random situations where emails were not parsed correctly. Part of the email was chopped out, for example:
Hi Test,\n\n-This is a test
Will result in -This is a test fragment being hidden and considered as part of signature which it should not be. After digging more into the problem, we figured out that:
(?m)(--\s*$|__\s*$|\w-$)|(^(\w+\s*){1,3} ym morf tneS$)
The first matching group is testing against \w-, which is causing the problem. I can't think out of a better way to solve the problem other than take \w-$ part out so it opens to any suggestion.