The 21st Century Integrated Digital Experience Act, which was signed into law on December 20, 2018, set into motion legislation that should accelerate e-signature adoption within the U.S. federal government, William Blair analyst Justin Furby tells investors in a research note. The analyst believes digital signature usage within the federal government has lagged that of the private sector. He estimates the U.S. federal government opportunity is "conservatively" anywhere from $280M to $500M-plus of total addressable market. As such, the analyst views the passing of the 21st Century IDEA Act as an incremental catalyst for DocuSign (DOCU) that should provide an additional growth lever over the next couple of years. He keeps an Outperform rating on the shares. Further, the analyst sees minimal, if any impact to the competitive landscape in the wake of Dropbox's (DBX) Acquisition of HelloSign. DocuSign has an integration with Dropbox that will continue going forward, says Furby. He remains a buyer of DocuSign shares and sees the potential for "significant" estimate revisions in the coming quarters.