For our group it would be helpful to understand what the preferred signature format is. For example, we could let folks know that anything after ten dashes ---------- would be parsed as a signature. We could then be in contact with our most difficult signature offenders (those that include images as part of their signature) and ask them to prepend their signature line with ten dashes. I realize this method wouldn’t work for everyone, but it would be very helpful for our smaller group (300 members).
Or possibly include something in the Admin that allowed us to specify our own local signature formats that would be stripped from incoming emails.