I received an email that said the IRS had sent a document for my signature through docusign; is this valid?

Were you using the TT Live program where you had a professional do your return ?

Probably not, unless you are working with the IRS already to resolve some sort of tax matter (other than simply filing your returns), I would be very skeptical that it is a valid request.

The IRS does not communicate with taxpayers through email.  They use the US Postal Service.

Take a look at the following article for more information and advice from the IRS about what to do if you get an email or phone call from someone claiming to be the IRS:  Report Phishing