Apple Mail 7.3 (1878.6) in OS X 10.9.5 (13F1507) with many folders stored locally. I began copying to IMAP servers – first to iCloud, then to the [Google Mail] area of Gmail.

The problem

Wherever an original folder contains messages and a sub-folder, the messages are not copied to the corresponding folder on the IMAP server. Instead:

  • on the server, an additional   (Messages) folder alongside the required folder
  • the additional folder contains messages alone
  • Mail can not move those messages from the   (Messages) folder to the required folder.

For example, an original folder containing messages and subfolders:

  • Safari

– the copy performed by Mail results in two folders at the same level:

  • Safari
  • Safari (Messages)


Can I force Mail in Mavericks to preserve folder integrity – content – when copying to a server?


I'm fairly certain that the problem did not occur with an earlier version of Mail.

Mozilla Thunderbird 38.5.0 can move messages on the server to the required folder, but doing so for hundreds of folders – and then deleting the debris – would be unnecessarily time-consuming …

… so I ceased using Mail to attempt copies to servers.

The separation when copying is highly undesirable. (I have thousands of folders, with a well-organised hierarchy. If Mail adds hundreds of additional folders, for messages alone, that organisation will be spoilt.)

When Mail performs an export, no separation is apparent.

The move away from local storage (copying to servers, then deleting originals) is part of a broader move away from Apple Mail.


After offering the bounty I spent a few hours performing additional tests.

The problem seems to be intermittent. Sometimes Mail does copy to Gmail, or iCloud, without the separation.

I tested with two Exchange servers, no problem. I tested with the IMAP port to one of those Exchange servers, no problem.

From the results to date, I can not draw any conclusion.

At one point, with iCloud, Mail tried and failed to create a separate folder for messages, with a report that the folder already existed on the server. However: neither Mail, nor the web interface to iCloud, showed that folder. That discrepancy makes me wonder whether the intermittent separation is a side effect of problems with IMAP subscriptions …

  • Is it worth updating this for mojave and a specific mail service? I would be happy to dump another bounty if this is still needed – bmike Jan 12 '19 at 14:19

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