[Build ID] > Mozilla/5.0 (Windows NT 5.1; rv:22.0) Gecko/20100101 Thunderbird/22.0a1 X-Mozilla-Keys: header(to hold Tag data in message source) is not added when mail copy from maildirstore/IMAP folder to maildirstore/local folder. So, if Mboxname.msf is intensionally deleted by user or Mboxname.msf is completely broken accidentally, Tag of mail is lost.

Checked with trunk nightly. > Mozilla/5.0 (Windows NT 5.1; rv:38.0) Gecko/20100101 Thunderbird/38.0a1 Copy 4 mails in Inbox of Gmail IMAP(MaildirStore, Offline-Use=Off) to FolderX of Local Folders(MaildirStore). 4 mails are normally copied to FolderX\cur directory of Local Folders, and X-Mozilla-Keys: was added.. So, problem of this bug is aready resolved. However, when Tag is already added to imap mail, nothing was written in X-Mozilla-Keys: header, This is same in BerkleyStore. However, if BerkleyStore, Tag held in msgDatabase is physically written to X-Mozilla-Keys: header in msgStore file by Compact. (design was so, but I don't know about current behaviour) So no problem. But if MaildirStore, because MaildirStore doesn't support Compact, this "tag already held at imap server" won't be physically written to X-Mozilla-Keys: header in msgStore file. Compact of local mail folder/BerkleyStore. 1. When no X-Mozilla-Status:/X-Mozilla-Status-2:, first Compact adds X-Mozilla-Status:/X-Mozilla-Status-2:only. 2. When X-Mozilla-Status:/X-Mozilla-Status-2: exists, if no X-Mozilla-Keys:, adds X-Mozilla-Keys:. So, X-Mozilla-Keys: is added by second Compact. IIRC, Tag held in msf was physically written X-Mozilla-Keys: in msgStore file by Compact, but I'm not sure. In today's test, "tag already held at imap server" was not written to X-Mozilla-Keys: header by Compact. If "tag already held at imap server is not written to X-Mozilla-Keys: upon copy to local folder" is spec of Tb, "Compact is not supported by Maildir" may produce problem of "Tag is lost by Repair folder if local MaildirStore". Anyway, problem of this bug(no X-Mozill-Keys:) is already resolved, Closing,