Our server infrastructure did at no point in time use any vulnerable version of OpenSSL. A change of the user password is therefore not necessary.
Regardless of Heartbleed, Signavio still recommends regular password changes to its users. Especially if you are using the identical password for different systems (some of which might have been actually affected by Heartbleed).
As a precautionary measure we will change all of Signavio's server SSL certificates during the next weeks.