Email Backup Strategy

I manage my iCloud email via Apple Mail ( I have limited knowledge of the workings of email and servers, but my understanding is that this is an IMAP account and hence all the mail (Inbox, Archive, Sent Items) is stored on Apples servers. I have a couple of questions…

  1. Is there a copy of this email stored locally on the Mac as well? I have done a search for files of type .mbox but nothing is found?

  2. Can I use ‘On My Mac’ as a ‘backup’ by copying the mailboxes across? Is this what creates the mbox files? (I have other system wide backups, Backblaze/Time Machine but I would prefer a separate backup of the mailboxes that I could turn to if ever need be).

Thank you.


You can find the mail files in ~/Library/Mail/V8. There are a number of obscurely-named folders in that folder (one for each mail account that you’ve configued). These folders contain the .mbox folders. There are usually multiple .mbox folders. For example INBOX.mbox, Sent Items.mbox, and so on.

In Mail > Preferences > Accounts you can decide whether you want attachments stored locally for each IMAP account, including iCloud. Otherwise, the messages are stored locally as well as online – this is normal for IMAP configurations.

It’s best to let your mail client manage your mailboxes, and synchronize them for you. It’s also best not to muck around inside of mail folders.


FWIW - If you ever want a dedicated email backup, I have used Horcrux ever since it was recommended by Adam Engst at TidBITS.


Hi tjluoma. Do you know if timemachine backs up emails in any useful manner? I presume it does if I can restore it to a new device quickly enough?

Hi Vincent. Welcome to the forums!

I don’t know the answer to that question. For one, it may depend on the email system that you use. For example, if your email is on an IMAP server, you can just re-download them from the server on a new device.

It also depends on which app that you use:

  • I don’t know if stores its messages is a way which can be moved to another Mac.

  • I know that MailMate can.

  • I believe that Outlook stores things in its own database format (or at least used to).

I believe stores files in an MBOX format, which is pretty common.

Therefore, backing up with Time Machine would backup these files as well. I do similar - I have Postbox download copies of all my email to my local machine, and then Arq backs up these files (MBOX files), so I could import these in to another mail program that supports MBOX’s at a later date. This way I get versioned copies of it as well, so I can roll back in time.

Do you use postbox only for backup purposes? I realized that I bought a lifetime license many years ago but never really used it. I’ve decided to start archiving/backing up my email.

I use The Email Archiving Solution for Professionals - Moth Software - works very well and support emails get a quick reply.

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No, it’s my standard email client for personal emails (I use Outlook for work emails, because, well, it works and it’s what the University officially supports).

Postbox is built on Thunderbird, which I like, but has a better theme, layout and tweaks than Thunderbird. It also integrates better with the Mac, and is able to use Contacts, rather than rely on it’s own internal address book (but does support that as well).

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Both Horcrux and Mail Archiver X look interesting.

I had another idea. My Synology can function as an IMAP server, so I installed that package. In my mailbox I created sub folders for each of my email accounts that I use in, and wrote an AppleScript triggered from Keyboard Maestro that takes the selected email messages and move them to the Synology into the proper folder based on the email account they were in.

All emails can be searched and browsed in, but these archives no longer clutter my “outside” IMAP providers and mailboxes. On the Synology they are stored in a text file format, similar to but not identical to MBOX format so they can be easily backed up via HyperBackup to the cloud.

I will see how this works out over the next few weeks.

This is especially interesting for me. Please keep the updates coming!

Been trying both Mail Archiver X and Horcrux. I landed on the latter, as Mail Archiver X seemed to be quite a resource hog and – critical for me at the time – would not be very considerate of the main drive space, which is a huge issue with a small SSD.
Horcrux is leaner (even if it could be even leaner to my taste…) and does its job well and silently. I’m happy with it, thanks for the recommendation. :slightly_smiling_face:

FYI - Mail Archiver X is currently for sale for $4 as part of the current BundleHunt deal.

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I guess it depends how often and when you run it.
Mine has a schedule at 4am to archive emails within the past 2 weeks, it takes about 20 minutes maybe.

My email backup strategy:

  • Export mbox file from email address.
  • Combine it with last backup mbox file to produce new mbox backup file.
  • Place backup mbox file on hard drive.
  • Repeat.

I’ve tried the following apps:

I found MailSteward the clear winner for my strategy. EagleFiler did more than I was asking. It too didn’t export mbox files properly, it created a folder “mbox.mbox” which couldn’t be opened. Horcrux was an automatically functioning app, which requires email credentials (I want to manually deal with mbox files). Mail Archiver X unfortunately didn’t combine mbox files into 1 when exporting, instead exported mboxs individually imported earlier. I did this research over a span of 2 hours, so take it with a grain of salt. Hope it helps!


I used MailSteward at work several years ago and considered it a good product.

FWIW, the file EagleFIler creates when importing email messages is an MBOX file (named “Archive” in the following image of my eflibrary). I’ve never needed to export it since Apple Mail will import it directly from the EF Files folder.

Screen Shot 2021-07-25 at 5.38.57 AM

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