updated 12:49 am EDT, Fri November 1, 2013
New anomalies, bugs apparently slipped through testing
AppleSeed developers are being contacted by Apple by email asking for help in testing an updated Mail application for OS X Mavericks. Some users have reported issues with the program including messages not correctly being marked "read" or "unread," odd GMail folder behavior and undoing operations, among other issues. The problems don't appear to affect all users of Mavericks, but bug reports have apparently been persistent enough to warrant urgent correction.
The email from Apple (seen below) asks that the new update be tested through normal use "as soon as possible," which suggests that the company would like to get the update out very quickly. While boasting relatively few new "front-facing" user features, Mavericks is a substantial under-the-hood upgrade with over 200 new features, many that are mostly invisible in day-to-day use (such as the "compressed memory" feature), and consequently a number of bugs have emerged once the product began being deployed across the Mac user base.
Testers are being asked to focus on moving messages into different folders, undoing certain operations (like deleting messages), ensuring that items marked as unread and read are consistent with the server and other aspects of normal, everyday use of the program. AppleInsider reports that Apple is particularly interested in email accounts from iCloud, GMail and Microsoft's Exchange servers, suggesting that the issues might be IMAP-centric.
There have also been reports of Mail having issues with notifications and incorrect filtering. Others, including MacNN staffers, have not seen issues with Mail since upgrading to Mavericks.