Fix Manual IMAP Copy Dates in Outlook
Why Manual IMAP Copy Shows the Wrong Date in Outlook
Many users and administrators attempt to migrate emails between mail servers by adding both IMAP accounts to Outlook and dragging or copying messages from one account to the other. This manual approach uses Outlook as an intermediary: Outlook downloads the email from the source IMAP server, then uploads it to the destination IMAP server using the IMAP APPEND command. During this upload, the destination server adds a new Received header with the current timestamp.
The manual IMAP copy approach has no mechanism for preserving the original INTERNALDATE. Unlike dedicated migration tools (which at least attempt to set the INTERNALDATE during APPEND), Outlook's copy operation does not pass a date parameter to the destination server. The destination server sets the INTERNALDATE to the upload time, and adds its own Received header. Both date sources now reflect the copy date rather than the original received date.
Users who perform manual IMAP copies often do so because they believe it is the simplest approach, or because they are moving a small number of emails. However, even a small manual copy can corrupt dates for hundreds of messages if an entire folder is selected. The date corruption is not apparent until after the copy is complete, when the user notices that all copied messages now show the copy date in Outlook's received column.
How This Affects Outlook
After a manual IMAP copy, Outlook displays the copy date for all transferred messages. The "Received" column shows when the message was copied, not when it was originally received. If the user deleted the originals from the source server, there is no way to see the correct dates in Outlook without fixing the headers.
The impact is identical to a migration tool-caused date corruption: sorting, searching, and filtering by date all operate on the copy timestamp. Outlook's date-based groupings (Today, Yesterday, This Week, etc.) are disrupted. Unlike migration tool scenarios that typically affect an entire mailbox, manual IMAP copy date corruption may affect a subset of the mailbox (only the folders or messages that were manually copied), creating an inconsistent mix of correctly-dated and incorrectly-dated messages within the same mailbox.
Frequently Asked Questions
I only copied a few folders manually. Can Redate.io fix just those?
Yes. Redate.io scans the entire mailbox and identifies only the emails with corrupted dates (where the INTERNALDATE does not match the original Date header). It fixes only the affected messages, leaving correctly-dated emails untouched.
Is manual IMAP copy worse than using a migration tool?
In terms of date corruption, the result is the same: the destination server stamps messages with the upload date. Manual IMAP copy through Outlook is actually worse in one respect: it does not attempt to set the INTERNALDATE, whereas some migration tools at least try to preserve it.
Can I prevent date corruption when copying emails between IMAP accounts in Outlook?
Outlook does not support setting INTERNALDATE during IMAP APPEND. There is no way to prevent date corruption when using Outlook to copy between IMAP accounts. If dates were corrupted, Redate.io can fix them after the fact.