Microsoft Graph API Integration Services

A security review at a healthcare scheduling SaaS found four service accounts with mailbox-wide access, and nobody on the engineering team could say which features still needed them. The accounts dated from an era of quick fixes: polling scripts reading every mailbox to catch booking confirmations.

We rebuilt the mail layer properly. Webhook subscriptions now notify the platform when a relevant message arrives, application access is trimmed to the specific shared mailboxes involved through an access policy, and the app registration documents every scope alongside the feature that needs it. The polling infrastructure was deleted rather than migrated. The engineering lead measured the change two ways: booking confirmations that once appeared within five minutes now appear within seconds, and the next security questionnaire took an afternoon instead of a week. Because the product serves many customer tenants, the consent model follows our multi-tenant pattern.

For a single internal automation, a Power Automate flow reaches the same endpoints without any code to own, and that is the right first answer more often than agencies admit. Custom engineering belongs where products meet scale: webhook-driven behaviour, multi-tenant consent, throttling budgets, and permissions a security team will interrogate. If your need is a weekly report landing in a channel, build the flow, and come back when the flow starts being load-bearing.