Twice in the last month I've noticed emails/messages not being mirrored to google groups, though they do go to the other recipients. * The first was one I sent on January 4th to mozilla.dev.platform. The title was "Some recent Treeherder improvements". * The second was one sent by Dave Hunt on January 19 to mozilla.tools.treeherder. The title was "Building a dashboard for test outcomes" Needinfo'ing :daveio, who seemed to be involved in a similar bug a week or so back (bug 1328960)
I think you'll need :limed for this as they handled the earlier bug.
Can you please provide me with mail headers of the missing email