Disclaimer text: is there any point to it?

Yes a well worded disclaimer clause that is clearly stated will be enforceable. There are a number of different types of disclaimers or exclusion clauses. One type you have identified is on the bottom of emails but they are also found in most consumer contracts such as gym agreements, mobile phone contracts etc. They are enforceable as by signing those documents you are stating that you have read and understood the terms of the agreement and consent to waiving your rights. Exclusion clauses are also found in car parks, again if clearly displayed and worded will be enforceable. My advice is always make sure the clause clearly states what you are excluded, if it is vague it will be unenforceable.

In terms of indemnify the company from inappropriate - remember you are vicariously liable for the actions of your employees. That means in simple terms -- you are responsible for every idiot you employ and the actions of that idiot. However if you have a clear social media and email policy then it could be a disciplinary action against the employee.