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Exporting/archiving email from Mail.app #

Michael Tsai has hosted a long-running discussion on data loss in Mail.app starting in Catalina and continuing unabated through Big Sur and Monterey (I have settled on only moving messages from IMAP servers to local storage via Thunderbird).

Further, Mail's built-in export (and import) methods suffer from various limitations and bugs; the following tests were run under macOS 12.4 and Mail 16.0 (3696.100.31):

1. Mailbox → Export Mailbox...

1. Creates a single MBOX file containing all messages (actually a slightly nonstandard folder with the mbox file named "mbox" and another file named "table_of_contents").

2. Pro: Successfully exported all messages.

3. Con: Attempting to import such MBOX files (containing any significant number of messages) back into Mail generally fails with the following error: Some messages could not be imported. The partially imported mailboxes are located in the mailbox named "Import" in the mailboxes list.

4. While Mail displayed a count of 4611 messages for the mailbox, 4618 were shown in Claws Mail and Thunderbird after import.

2. Click and drag multiple messages from Mail to Finder

1. Creates a single EML file per message (converting from Mail's native EMLX format, which stores attachments separately) as opposed to MBOX's monolithic single file format.

2. Pro: Works on even large numbers of messages (tested on a selection of over 10,000 - see below).

3. Con: Silently fails to export messages with subject lines 252 characters or longer.

4. When performed on the aforementioned mailbox (which Mail showed as containing 4611 messages while the exported MBOX file was reported to hold 4618), only 4600 messages were exported. The missing messages all had subject lines over 251 characters in length. This was verified by getting a list of all subjects in the mailbox via AppleScript (which also returned 4618 instead of 4611):
   
tell application "Mail" to get the subject of every message of mailbox "foo"
set subjectList to result
set AppleScript's text item delimiters to "\n"
set subject1PerLine to subjectList as string
get subject1PerLine

   then locating those containing 252 or more characters: grep '.\{252\}' subjects.txt. Sure enough, the difference was exactly 18.

5. Mail reported 10,663 messages in another mailbox; however, clicking and dragging them to a folder in Finder resulted in 10,672 EML files, indicating once again that Mail has a hard time keeping track of messages.

3. AppleScript

1. Tom Floeren's 2017 "Export Selected Mail Messages" AppleScript still runs under Monterey, exporting highlighted messages to EML files.

2. Pro: Truncates subjects/filenames over 180 characters to avoid the con described in 2c.

3. Con: 31 messages were missing from the export after the script terminated with Script Error: AppleEvent timed out. Happily, this was easily rectified by adding with timeout of 3600 seconds above repeat with i from 1 to count of msgSubjects and end timeout below end repeat; afterwards, all messages exported successfully. (UPDATE: See Michael Tsai's post for another potential issue affecting non-ASCII characters under some circumstances.)

4. As in 1d and 2d above, 4618 messages were exported from the mailbox which Mail had reported as containing 4611 messages. As a final test, ran this simple AppleScript oneliner to get the number of messages in the mailbox: tell application "Mail" to get the count of messages of mailbox "foo"; the result was 4618.

5. Updated script:
   # Name: Export Selected Mail Messages # Description: Exports selected mail messages from Apple’s Mail app as .eml # Web page: <http://dflect.net/bulk-export-selected-mails-from-apple-mail/> # Author: Tom Floeren <tom@dflect.net> # Created: 2017-02 # Last modified: 2022-06-14 (by Miles Wolbe to resolve "AppleEvent timed out"; # see https://tinyapps.org/blog/202206140700_mail-app-export.html for details) # Version: 1.0.1 # # Copyright © 201X-2017 Thomas Floeren # # Permission to use, copy, modify, and/or distribute this software for any # purpose with or without fee is hereby granted, provided that the above # copyright notice and this permission notice appear in all copies. # # THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH # REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY # AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, # INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM # LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR # OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR # PERFORMANCE OF THIS SOFTWARE. use AppleScript version "2.4" -- Yosemite (10.10) or later use scripting additions set exportDestination to missing value # If you like, set your export folder here (HFS notation = separate path components with a colon “:” + trailing “:”) # If you don’t set a folder here the script will ask you each time for the destination. # Some examples: --set exportDestination to (path to desktop) & "Exported Mails:" as text --set exportDestination to (path to documents folder) & "My Mails:" as text --set exportDestination to (path to home folder) & "My Backup Folder:Exported Mail Messages:" as text set fieldSeparator to space set msgSubjects to {} set msgDates to {} set msgSenders to {} set msgSources to {} set msgCount to 0 # Ask for destination (if no path is set at the beginning of the script) if exportDestination is missing value then set exportDestination to chooseFolder() as text # Start stop watch set timeStart to current date # Grab the messages tell application "Mail" set selMsgs to the selected messages of the front message viewer if selMsgs is missing value then my alertNoSelection() error number -128 end if repeat with theMsg in selMsgs set {end of msgSubjects, end of msgSenders, end of msgDates, end of msgSources} to {subject of theMsg, sender of theMsg, date received of theMsg, source of theMsg} end repeat end tell # Write messages to file with timeout of 3600 seconds repeat with i from 1 to count of msgSubjects set {theSender, theSubject, theDate, theSource} to {item i of msgSenders, item i of msgSubjects, item i of msgDates, item i of msgSources} set saveTID to AppleScript's text item delimiters # Format sender # Full email address --set AppleScript's text item delimiters to {"<", ">"} # Email address without TLD set AppleScript's text item delimiters to {"<", "."} set theSender to text item -2 of theSender # Format date/time as short ISO set AppleScript's text item delimiters to {""} set theDate to theDate as «class isot» as string set theDate to words 1 thru -2 of theDate as text set theDate to text 3 thru -1 of theDate # Format subject # ':' is the only forbidden character on macOS. You can add more characters if you want, for example '{".", "?", "/", "<", ">", "\", "|"}' set AppleScript's text item delimiters to {":"} set theSubject to every text item of theSubject set AppleScript's text item delimiters to {"-"} set theSubject to theSubject as text set AppleScript's text item delimiters to saveTID # Compose file name set msgFileName to theDate & fieldSeparator & theSender & fieldSeparator & theSubject # Limit file name length # Max is 255, but decomposed characters like ü, ä, é etc. count as two characters (UTF-8 NFD!); so we better have some margin. if (count of msgFileName) > 180 then set msgFileName to text 1 thru 180 of msgFileName set msgFileName to msgFileName & ".eml" # Save to file try set newFile to (open for access file (exportDestination & msgFileName) with write permission) on error errMsg number errNum if errNum is -43 then alertDestination(exportDestination, errNum, errMsg) else if errNum is -1410 then alertNameLength(msgFileName, errNum, errMsg) else alertOther(errNum, errMsg) end if error number -128 end try write theSource to newFile close access newFile set msgCount to msgCount + 1 end repeat end timeout # Read stop watch set timeElapsed to (current date) - timeStart # Display stats display alert "Completed" message "Exported " & msgCount & " message(s) in " & timeElapsed & " seconds to “" & (POSIX path of exportDestination) & "”." as informational ------------------------------------------------------------------------ # Handlers on chooseFolder() tell application (path to frontmost application as text) set dest to (choose folder with prompt "Pick a folder to export your mails to:") end tell return dest end chooseFolder on alertNoSelection() display alert "No Message Selected!" message "Select one or more messages in the messages list and run the script again." buttons {"Got it!"} end alertNoSelection on alertDestination(dest, eNum, eMsg) # -43 display alert "Destination folder missing or not accessible" message "Please check the folder path you have set at the beginning of the script or check the write permissions of the destination folder:" & return & return & dest & return & return & "# Error number:" & return & eNum & return & return & "# Error message:" & return & eMsg as critical end alertDestination on alertNameLength(fName, eNum, eMsg) # -1410 display alert "File name too long" message "Because of a very long Subject line the file name of this email message is too long:" & return & return & fName & return & return & "Please lower the file name length limit in the script." & return & return & "# Error number:" & return & eNum & return & return & "# Error message:" & return & eMsg as critical end alertNameLength on alertOther(eNum, eMsg) display alert "An error has occurred" message "The following error has occurred:" & return & return & "# Error number:" & return & eNum & return & return & "# Error message:" & return & eMsg as critical end alertOther

4. partial-emlx-converter

1. Open source script that "converts .emlx and .partial.emlx files written by Apple's Mail.app into fully self-contained, 'stand alone' .eml files."

2. The author, Philipp Katz, relates that "one of my IMAP mailboxes went out of service and I was not able to copy all the messages to a different account with Mail.app, even though all mails and attachments were there (see here for the story). That’s why I created this script."

3. Pro: Successfully converted all 4618 messages in test mailbox to EML format.

4. Con: Not native.

Updates

• Mail Exporter Pro, mentioned back in 2017, offers fast, robust exporting to a number of destination formats, including Entourage/Outlook, PST, Apple Mail Mailbox (Archive), Thunderbird/Postbox, MBOX, and EML.

• Import EML files into Mail.app (tested in version 16 under macOS 14 Sonoma):

  1. Add EML files to a directory (e.g., "In")
  2. Add an .mbox extension to the directory ("In.mbox")
  3. In Mail, click File → Import Mailboxes... → select "Apple Mail" as the format → Continue
  4. Browse to and select directory ("In.mbox") → Choose → Continue → Done.

/mac | Jun 14, 2022

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