We had a bug impacting emails sent today between roughly 9:55am-10:35am ET, causing emails to be sent with recipients listed in the “To” field instead of being BCC’d. The bug initiated during a migration to the new version of SendGrid’s API; we have rolled back to the pre-deployment version, and further emails have not been impacted.
Approximately 230 emails were sent to 73,205 recipients during that time; however, only emails that did not use any tag replacement should have been affected, so the actual number impacted is lower.