During the MailMax 5.5 installation I get this error:
[Microsoft][ODBC SQL Server Driver][SQL Server]Violation of PRIMARY KEY constraint 'PK_Conections'. Cannot insert duplicate key in object 'Connections'.

Resolution:

During the 'Domain and Email Account Setup' dialog, you entered the IP address of 127.0.0.1 for the primary domain. By default, 127.0.0.1 already exists in the MailMax database therefore giving you this error.  The IP address you enter MUST reside on the server and be properly configured in your DNS. If you decide to use 127.0.0.1, you will only be able to send mail locally on your server.

Click the 'OK' button to continue with the installation. This error will not cause any damage to the installation.