The Outreach 'Send now' button in Gmail is no longer purple and shows the native blue Gmail Send button instead.
There are two solutions:
1. Reach out to your org's admin and have them enable the prospect auto-create option
2. Add at least one Outreach prospect to the To: line
The email address in the To: field does not match a current prospect in Outreach and your org's admin has not enabled to the prospect auto-create option in the general org settings.