Do I need to integrate this platform for email sending?

Yes, if you want event data to trigger or update email marketing workflows in Marketo, Eloqua, or another connected app, you use Certain Signal Connector to send outbound data from Certain to that system. Certain Signal Connector: Marketo Native Integration Guide Signal Connector Integration with Advanced Webhooks Guide

If you mean sending standalone emails from Certain itself, that is not what these Signal Connector guides cover. They describe outbound data syncing, not email delivery inside the platform.