Exporting mbox - File size significantly smaller - How to make sure a full and clean export?

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Level 1

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Exporting mbox - File size significantly smaller - How to make sure a full and clean export?

Dear All,

My Mac is running out of space and I'm considering a mail export to re-locate my mail archives online.

However, the exported mbox is much smaller than some folders (checking their size with "mailbox information" from Apple Mail).

How can I make sure that my mailboxes are exported without errors or missing e-mails?

Is there some kind of log to help me confirm that the export was successfully completed?

I've read many of the threads here, have done a rebuild of indexes, but that did not change anything.

Thank you!

MacBook Air, macOS 13.2

Posted on Mar 27, 2023 5:15 AM

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Answer 1

Top-ranking reply

Matti Haveri

Level 6

19,988 points

Mar 27, 2023 6:09 AM in response to junkan

"for some weird reason Mail.app can export only up to 2.15 GB mailboxes so old messages are silently ignored! BTW, remember to choose "Export all subfolders" option, if necessary!"

Does that explain the issue?

My memo to archive or transfer Mail.app mailboxes:

a) zip the ~/Library/Mail folder and copy it to the other account.

b) Or optionally in Apple Mail > Mailbox > Export Mailbox... But for some weird reason Mail.app can then export only up to 2.15 GB mailboxes so old messages are silently ignored! BTW, remember to choose "Export all subfolders" option, if necessary!

Then in another account:

Mail > File > Import Mailboxes... > Apple Mail > choose that ~/Library/Mail folder > choose all Items.

On the left-hand-side under "On My Mac" > Import, ..., look for and move "Local" and all mailboxes inside it up under "On My Mac". Right-click and you might delete "Import" folder (it has gmail mailboxes that are online). YMMV.

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Answer 2

Mar 31, 2023 7:31 AM in response to junkan

> My old email archives contain some legal stuff (hence their importance) and are close to 200GB in total. I’d like to focus on having a trustworthy export

I occasionally just zip and archive the ~/Library/Mail folder. I believe I can then import or re-export it to other formats anyway I like.

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Answer 3

junkan Author

Level 1

9 points

Mar 27, 2023 5:28 AM in response to junkan

Just wanted to share a workaround that I tried, but without success.

I took a mailbox (a local one) in Mail, rebuilt the index, and could see that it contained 4084 mails.

I selected them all to copy them (as individual .eml files) in a dedicated folder...

And I ended up with 2723 files instead of 4084.

Very frustrating and deteriorating my trust ;-)

Thanks in advances for your opinions and guidance!

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Answer 4

junkan Author

Level 1

9 points

Mar 27, 2023 6:14 AM in response to Matti Haveri

Thanks a lot for sharing the experience.

Considering an upload (in this case to Proton Mail), a zip file of the Mail folder won't allow me an import?

Are we really stuck with a "monolithic" file that we can only view through Mail, and which we can't be sure of the actual content?

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Answer 5

junkan Author

Level 1

9 points

Mar 27, 2023 8:05 AM in response to Matti Haveri

Thanks for the recommendation!

The tool itself (which we can try before we buy, that is nice!) reports a much lower number of emails than Mail app.

Mail app shows a folder with more than 42000 mails, and the exported MBOX shows a funny 25.3MB...

I'll still reach out to the software to see if the problem really is with my emails and if I can recover anything.

I'll keep the thread updated.

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Answer 6

tbirdvet

Level 6

17,295 points

Mar 27, 2023 12:47 PM in response to junkan

If you are running out of space perhaps you can offload videos, movies, photos that take up much more drive space.

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Answer 7

Mar 27, 2023 7:00 AM in response to junkan

If you want to export and archive such large mailboxes in some custom mailbox format, one workaround is to use Emailchemy to export ~Library/Mail folder. I used it when I had trouble importing El Capitan mail to Mojave mail (it did the transition OK while my other approaches either skipped or duplicated messages).

https://weirdkid.com/emailchemy/

BTW recently I used PST Converter Pro to convert Windows Outlook .pst to Monterey Mail.app (I later noticed that Emailchemy could that task as well). "PST Converter Pro" handles only PST files so that won't work in your case.

...I had some largish >2.15 GB .pst mailboxes and then I noticed that Mail.app export issue.

https://apps.apple.com/fi/app/pst-converter-pro-apped/id446401009?mt=12

...

https://discussions.apple.com/thread/8120062

Windows 10 Outlook .pst to Mail - Apple Community

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Answer 8

junkan Author

Level 1

9 points

Mar 27, 2023 10:02 PM in response to tbirdvet

Thank you, I realise that this is in general a good suggestion, but I have already taken these steps. My old email archives contain some legal stuff (hence their importance) and are close to 200GB in total. I’d like to focus on having a trustworthy export.

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Exporting mbox - File size significantly smaller - How to make sure a full and clean export?

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