Google Workspaceでのimapsync移行日付の修正

imapsync is a popular choice for migrating メールボックス to Google Workspace because it is open-source, scriptable, and supports the IMAP protocol that Google Workspace exposes. ただし、 Google Workspace's IMAP implementation has specific behaviors that interfere with date preservation. When imapsync uploads messages via IMAP APPEND, Google's mail infrastructure processes each message through its own pipeline, adding a Receivedヘッダー and potentially overriding the INTERNALDATE.

The --syncinternaldates flag in imapsync instructs the tool to request the original INTERNALDATE from ソースサーバー and pass it to 宛先サーバー during APPEND. Google Workspace may accept this date for some messages but override it for others, depending on the message content and how it passes through Gmail's filters. The result is an unpredictable mix of messages with correct and in正しい日付s within the same migrated メールボックス.

Google Workspace 管理者 often discover the problem when ユーザー report that their Outlook or Apple Mail clients (connected via IMAP to their Google Workspace account) show in正しい日付s. The Gmail Webインターフェース 通常 shows 正しい日付s (using the Dateヘッダー), which adds to the confusion. A Google Workspace メールボックス can appear perfectly normal in the browser while being completely date-corrupted from the perspective of any IMAP client.

The split between Gmail web (showing correct Dateヘッダー dates) and IMAP clients (showing corrupted INTERNALDATE) is the defining characteristic of this issue in Google Workspace. Organizations where some ユーザー prefer the Gmail Webインターフェース and others use Outlook or Apple Mail experience inconsistent date displays from the same メールボックス. Collaborative workflows break down when colleagues reference email dates that appear differently in their respective clients.

Google Workspace admin tools provide limited visibility into the INTERNALDATE issue. The Google Admin Console does not expose INTERNALDATE metadata for individual messages. Google Vault, used for コンプライアンス and eDiscovery, may reference either the Dateヘッダー or the INTERNALDATE depending on the search method, producing inconsistent results in legal discovery scenarios. The only way to comprehensively resolve the issue is to correct the INTERNALDATE and Receivedヘッダーs at the message level.