“No. Opt-Inbox is fully supported as an add-on behind any existing email security platform: Microsoft 365 Defender, Proofpoint, Mimecast, Barracuda, Sophos, Trend Micro, and others. The Sendio bundle (ESG + Opt-Inbox) is an alternative deployment path, not a requirement.”
“Three reasons typically drive that choice: vendor consolidation (fewer contracts to manage), unified administration (one console instead of two), and native architecture (ESG is tuned for downstream Opt-Inbox identity enforcement). If those operational benefits aren't important to your team, the add-on path is often the simpler choice.”
“No, and Sendio doesn't position it that way. ESG implements standards-based email security reliably. The differentiator in the Sendio platform is not ESG's threat detection capability, it's the native two-layer integration with Opt-Inbox identity enforcement.”
“ESG security thresholds and bulk-handling rules are designed assuming Opt-Inbox identity enforcement runs downstream. Spam scoring is tuned more flexibly, IP reputation is calibrated knowing identity will handle desirability, and bulk mail handling defers to sender state. This produces fewer false positives at the security layer than traditional platforms that must guess at desirability without identity context.”
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