Stripping signature / tagline / adline

Is there any standard way to tell Mhonarc to strip the signature /
tagline / adline (for free email providers)?  In plaintext, they are
often deliniated by multiple dashes and a newline.  I think they are
delineated in html by a tag - but I'm not sure.

If not, and I write a little regex to do this, where is the least
invasive place to put it?