EWS should send email notifications to patch author when any failure is detected on a patch by EWS. We did a survey (https://lists.webkit.org/pipermail/webkit-dev/2019-December/030980.html) regarding notifications by EWS. Survey results indicated that most of patch authors want a notification when their patch fails any EWS. In contrast, most of the people do not want any notification when they are cc'ed on the bug (when they are not the patch author). Email notifications would help the patch author to know quickly when the failure happens on their patch, so that they don't have to keep checking Bugzilla for all the EWS queues to finish. Commenting on Bugzilla wouldn't be appropriate since it would create email notification for all the people cc'ed on the bug, and as per the survey most people do not want any notification when they are cc'ed on the bug (and are not patch author). Based on that, sending email notification to patch author seems like the most appropriate thing to do.
Most likely, I would also develop a way to unsubscribe from the email notifications, so that the people who do not like the email notifications can unsubscribe from them.
<rdar://problem/66995913>
Developed a way to unsubscribe from ews emails in Bug 215585.
Enabled email notifications for build failure and layout test failure in https://trac.webkit.org/changeset/266089/webkit
Announcement email: https://lists.webkit.org/pipermail/webkit-dev/2020-August/031358.html