Take a look at the T-SQL in the job step though, you will see that it executes something like this below.

exec [ReportServer].dbo.AddEvent @EventType='TimedSubscription', @EventData='35e240e6-6ca7-415e-8eeb-36a880d264b7'

There is no way of sending the email address and any other parameter through. Doing it this way you would still need to have the 100 subscriptions. The @EventData parameter references a row in the ReportServer.dbo.Subscriptions table.

If you have Enterprise Edition you can do what you want using Data Driven Subscriptions. You provide a SQL statement that returns the email addresses and the parameter values to use for the report. This can be done on a timed subscription as well, not just when data changes.

If you don't have Enterprise Edition then one way of doing this is using a SSIS package to render the report for each customer and then email it out. This TechNet article outlines an approach for this that I have followed a couple of times. https://technet.microsoft.com/en-us/library/ff793463%5B/url%5D