Apple MailでのGSMMO移行日付の修正

When GSMMO migrates emails from Outlook PST files or Exchange profiles into Google Workspace, it sets the INTERNALDATE to the upload timestamp. Users who subsequently connect Apple Mail to their Google Workspace account via IMAP see every migrated email dated to the GSMMO migration day. Apple Mail on macOS and iOS reads the IMAP INTERNALDATE to determine the date displayed next to each message.

Apple Mail does not parse the Dateヘッダー from the email body for its list view date display. Unlike the Gmail Webインターフェース (which uses the Dateヘッダー and may show 正しい日付s), Apple Mail relies entirely on the server-provided INTERNALDATE. This means the 移行日 is the only date Apple Mail displays, with no way for the ユーザー to see the 元の日付 without opening each message and inspecting the full headers manually.

Mac and iPhone ユーザー who migrated to Google Workspace using GSMMO and use Apple Mail as their primary メールクライアント are fully affected. Their inbox, 送信済みアイテム, drafts, and archived messages all display the 移行日. Smart Mailboxes in Apple Mail that filter by date produce incorrect results, and the chronological thread of email conversations is lost in the message list view.

Apple Mail on macOS displays the INTERNALDATE in the message list. After a GSMMO migration, every email shows the 移行日 に関係なく when it was originally sent or received. The "Date Received" column in Apple Mail's column view shows the 移行タイムスタンプ for every message. Sorting by date groups the entire メールボックス under a single date.

On iOS, the Mail app behaves identically. The inbox view shows the 移行日 next to each message. Smart Mailbox rules on macOS that use "Date Received is in the last [X] days" either catch everything (if the migration was recent) or nothing (if the migration was weeks ago). Spotlight search on macOS, which indexes Apple Mail messages and allows date-based filtering, also uses the INTERNALDATE, so system-wide email search by date returns incorrect results. The issue permeates the entire Apple ecosystem's email experience.