By Elliot Gulliver-Needham Software company Smartspace has received a £28.4m buyout offer (90p a share) from Sign In Solutions, the firm said today. Smartspace specialises in visitor and employee management software for offices, with headquarters in London, Texas and New Zealand. The AIM-listed company, which currently has a market cap of £20.9m, has seen previous declarations of interest from companies looking to take it private. Last year, Australian venue management software supplier Skedda attempted a takeover of the company for 82p a share, but eventually abandoned its plans. Smartspace’s…