How can I import mailing list data from an existing MySql / SQL Server online database?

Simply create a script in any server-side language (Asp, PHP, etc) which will show all your database records in a “csv” format (one record on each line, fields separated by comma or semicolon); then, when importing, tell SendBlaster the url of this page. This also applies to any online database, such as postgres, SQL server, etc.