All e-mails in DocRead are sent using the DocRead Notification Scheduler service (not using the email functionality that SharePoint offers). This means that the DocRead Notification Scheduler is a Windows Service that can run on a Windows Server that doesn’t require SharePoint.

At the time we designed scheduler, we thought long and hard about the best architecture and decided that our approach was best for a few reasons :

1. Cheaper License : The scheduler can be run on *any* Windows machine that can access the DocRead and Scheduler Databases. This can still be a SharePoint Application server if needed, but can also be a completely non-SharePoint server.
2. Performance : For larger customers DocRead can potentially send out a huge number of emails. (No. of Documents x No. Of Users x 3 types of email). Sending e-mails can be very CPU intensive and can cause long blocking calls, (especially if you email server is down/slow). Hence, we decided to keep this as a completely separate service, meaning it wont affect the overall performance of your WFEs or App Servers in the same way as if we’d built it as a SharePoint Timer Job for example.
3. Future-proof : We have a full roadmap of features for DocRead and as part of our future plans we intend to release more ways to notify users. The Scheduler service will facilitate this because it is stand-alone and can be secured or located where necessary to connect other systems. (e.g. in the DMZ).