Sendaware

Because SendAware uses Google’s own infrastructure without injecting tracking pixels:

SendAware is available in three tiers to suit individual users and large organizations. Enterprise Attachment Checking Recipient Blocking Encryption Prompts Centralized Admin Control Custom Branding sendaware

This is unique to SendAware; most competitors require pre-send activation. sendaware

Prevents accidental "Reply All" actions based on pre-defined message attributes. sendaware