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How to delete attachments in encrypted mails?

2017-01-29
2018-05-02
  • Zaphod Beeblebrox

    Dear all,

    I use Thunderbird (45.7.0) with the Enigmail plugin (1.9.6.1) on a Windows 10 notebook.

    I encrypt my emails with Enigmail for several years now , and I save all my emails. As Thunderbird seems to become slower and slower and my ssd fuller and fuller, I would like to save my encrypted correspondence WITHOUT the some huge attachments.

    So, is there any way to delete attachments from encrypted e-mails? I can save the attachments, but I cannot delete them. The size of my emails stays the same.

    Do I miss something?

    Thanks and best wishes
    Zaphod

     
  • Ludwig Hügelschäfer

    Hi,

    Thunderbird does not allow the separation of attachments from the mail body. A received mail is stored as a unit, and there's no possibility to pull the attachments out and free the stored size.

    Even, if there would be such a possibility, encryption and/or digital signature would make this impossible, without permanently decrypting the mail, which, for a part of the users is a no-no.

    But apart from these theoretical view: Did you try "File -> Compact folders"? This may reduce the size of your storage by already deleted messages.

     
    • Renny Jose Manuel

      I understood... Great! This is a helpful answer! Thanks Ludwig...

       
  • Patrick Brunschwig

    Actually, there is an option in Thunderbird to detach attachments. However, it is not possible to use such a function with encrypted mails - it would destroy the email.

    If you want to detach attachments, you first need to store the mail unencrypted (Context Menu on message > Decrypt to Folder)

     
    • ichier

      ichier - 2017-06-30

      i stumbled across that thing, too. especially for sent non-encrypted but signed messages whose text i want to keep this is annoying.
      i would not care, if the sent messages signatures will be broken.
      i alternativley wouldnt care, if the signature isnt even applied to messages stored in my sent folder...

       
    • Renny Jose Manuel

      Yes your're correct! True, it is pointless about thinking to detach the attachments from the encrypted mails... And thanks for sharing information on how to detach the attachments from the mails and the significant steps to decrypt the incoming mails...

       
  • Reality Exists

    Reality Exists - 2017-10-11

    I'm running into this as well, and it's quite annoying!

    Thunderbird does not allow the separation of attachments from the mail body.

    I'm not sure what you mean. If I right-click on an attachment in Thunderbird 52.4.0 there are "Detach..." and "Delete" menu items.These both work without encryption - I can delete an attachment, but keep the rest of the email. However, these menu items are disabled when the email is encrypted with PGP.

    I understand that deleting an attachment would make the signature invalid, but in my case the email is not signed, only encrypted. Also, even if it was signed, the user should have the option to ignore this, as ichier said (they've already verified the signature, after all).

     
  • Patrick Brunschwig

    That's the point. The "Detach..." option is disabled for PGP/MIME signed and PGP/MIME encrypted mails (but not for inline-PGP mails).

     
    • Reality Exists

      Reality Exists - 2017-10-11

      What's the point? Why can't Enigmail just take the decrypted email (what it's showing me), re-encrypt its remaining contents (text and any remaining attachments) and store that?

       
  • Patrick Brunschwig

    That would work in theory. But does the message need to be re-encrypted at all? If not, you can simply first create a decrypted version of the mail (even by filter rules) and then detach any attachments you like.

     
    • Reality Exists

      Reality Exists - 2017-10-11

      I would want it re-encrypted, yes, so that the plaintext is not stored in the mail server. Otherwise decrypting works as workaround, but it's still a bit of a hassle to do every time I want to delete an attachment. Ideally the existing Delete menu item should just work the same way whether the message is encrypted or not. My understanding is that Thunderbird already re-writes the message when deleting an attachment (from an unencrypted message), since an IMAP message is immutable on the server.

       

      Last edit: Reality Exists 2017-10-11
  • RT

    RT - 2018-03-13

    I bcc myself on all e-mails I send. I use POP3 more than I use IMAP. I am starting to use Enigmail to encrypt and sign my e-mails. I have received back bbc'd copies of two e-mails I'd sent with attachments, that I'd used Enigmail to sign (not encrypt). I can't delete the attachments from the e-mail - the option to do so is greyed out. I've tried "Decrypt to folder" but that doesn't do anything at all - it neither seems to decrypt the e-mail (it's not encrypted anyway), and it doesn't create a copy from which I can delete the attachments. Is there a workaround for this.? I frequently send large attachments and I can't keep multiple copies both within e-mails and also within my normal file structures.

    Also, is there any way of automatically decrypting any encrypted e-mails when I receive them (via POP3) and storing them unenecrypted rather than encrypted? Once I've safely received them, I no longer care about encryption as they're within my care. Anyway, the whole of my disk is encrypted and is decrypted on the fly.

     

    Last edit: RT 2018-03-13
  • Patrick Brunschwig

    The function is actually disabled for signed mails, because Thunderbird doesn't support it. If the function would be enabled, Thunderbird would print an error in the console, but do nothing. This is not the worst of all options, since deleting an attachment from a signed message would destroy the signature.

    Decrypting a signed-only message will do nothing, because the function does says what it says: "decrypt" - not "remove signature".

     
    • RT

      RT - 2018-03-13

      Thanks Patrick. I wonder if you'd consider this as an option (Remove signature)? In essence, I would be happy to know that something I'd received had been signed when I had received it (and was no longer), if it meant that I can detach and delete attachments, just like I can for an unsigned e-mail. It would undoubtedly be useful to know that it had been signed, but I'd love the option to remove the signature to make available other functions.

      Similarly, my only use for encryption of my e-mails (received and sent) is to ensure security of data during transmission Once on my computer, I want to store unencrypted so that I have no potential future issues with keys etc.

       
      • Olav Seyfarth

        Olav Seyfarth - 2018-03-13

        It would undoubtedly be useful to know that it had been signed, but I'd love the option to remove the signature to make available other functions.

        I second that. My usecase is that I want/need to remove big attachments from signed messages. I rather not permanently have the assurance that a messages was not tampered with that to not be able to remove files from it.

         
  • Marco Bade

    Marco Bade - 2018-05-02

    I just faced same annoying problem now that I sign all my mails. Anyway, I found myself an easy workaround that is a good compromise and does not need too much extra clicks. Once I have sent a signed message with attachments and want to save it to my harddisk as an eml-file without attachments, I simply click on "send as new". Then I deactivate signature (and encyrption) and save it as a draft. From the draft I can remove the attachments with one click as usual and then save the message. By this the saved message even still shows which attachments were removed. I missed that on other workarounds I tried first.

     

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