Electronic signatures - validated systems needed?

[Jedi]

Three questions:

1. please can you direct me to a guidance/regulation/recommendation that states that an electronic signature used in the GXP environment requires to be issued using a validated computer system?
2. If I can not find any "rules", thus would it be acceptable to use a non-validated computer system to sign any GXP documents with an electronic signature (e.g. using a non-validated DocuSign process) ?
3. Even if Q2 is answered with "NO" and rational is given using output of Q1, would it be acceptable to sign vendor contracts using a non-validated system for electronic signatures as the Legal Departments are considered outside the remit of GXP requirements, thus they could use non-validated systems for their electronic signatures?

Any thoughts are much appreciated. Thank you

[a123456]

Might be a good idea to look at the other threads below this one