[techsupporter]

You don't sign the letter because signatures have a way of magically[0] teleporting themselves onto documents that you've never seen.

0 - Using such fancy Merlin's wands of "Photoshop" or "scanning and then MS Paint copy/paste" or just "photocopy, cut with scissors, paste with tape, photocopy again."

[uiri]

That is highly illegal. The FCRA and related laws are enforced by the FTC, CFPB, and debtors' lawyers. However, forgery is a felony in all 50 states. If they forge your signature and mail it to you from another state, it becomes a federal crime. A creditor would have to be really stupid to try something like that.

[danieltillett]

I have always wanted a stamp that physically cuts out a complicated pattern as a signature.