Tue, 07 Apr 2026 19:28:17 +0000 https://bugs.horde.org/ticket/14811 Attachments get lost after drag&drop import If you drag and drop more than one attachment into your compose window you get a positiv upload information for each file (in the green window...). But the sent mail does not contain all the uploaded attachments. Atm I don't see a pattern which or why an attachments get lost. Wed, 18 Apr 2018 11:46:08 +0000 https://bugs.horde.org/ticket/14811#t92838 > If you drag and drop more than one attachment into your compose > window you get a positiv upload information for each file (in the > green window...). > > But the sent mail does not contain all the uploaded attachments. > > Atm I don't see a pattern which or why an attachments get lost. I would like to confirm this issue. Even in Chrome or in Firefox (latests versions), when drag and drop more than one file, sent message only contains one or two of attached files. Tue, 03 Jul 2018 10:09:54 +0000 https://bugs.horde.org/ticket/14811#t92905 We can confirm the bug as well. A confirmation box will be displayed for each file. Users therefore assume that all files have been sent. But this is not so. This is very unpleasant. Wed, 11 Jul 2018 06:29:52 +0000 https://bugs.horde.org/ticket/14811#t92920 The same here, current IMP/Horde versions, current browser versions. Please tell us, if we can help debugging this. Kind Regards, Frank Richter Wed, 01 Jul 2020 11:24:26 +0000 https://bugs.horde.org/ticket/14811#t93754 I have spent some time looking at this issue from different perspectives. Currently, I'm wondering if this bug may have been introduced by a change in common browser behavior, and not by a code change in Horde. What I noticed is that the problem of missing attachments only shows up when the upload of several files via drag-and-drop actually occurs at once, i.e. it only happens when these file uploads take place in parallel. The problem really manifests itself when the second upload requests completes before the first one is finished (or the third one before the second, etc.). So it's a matter of timing. I searched for ways to prevent that from happening on the client side (using Javascript), but that didn't prove successful, at least with my level of Javascript knowledge and given the concurrent nature of Javascript processing. So I ended up tackling this problem on the server side. Recently, I built a special configuration on our load balancer that will queue parallel Imp file uploads of the same session and only allow one upload request to proceed at a time (the second upload commences only after the first has finished), thereby serializing one user's upload requests. After this modification to server-side upload request timing, no more problems with drag-and-drop attachment uploads have come up. So my theory is: Could it be that common browsers formerly would only upload one file at a time in XML-Http-Request environments, but nowadays, they upload several files in parallel, and Imp/Horde is not prepared for this parallelized upload behavior? By the way, in case that others who are experiencing this trouble haven't noticed yet: this problem does not occur when clicking the "Add Attachment" link and selecting several files for upload in the file selection window. When uploading several files at once this way, only one HTTP upload request is generated which uploads several files in a row, as opposed to the drag-and-drop method, which creates several HTTP requests, and these, in turn, upload one file each. (One can make a distinction between these types of file upload requests, initiated either through drag-and-drop, or by clicking the link, on the HTTP level by examining the query parameters. While the upload URL is the same otherwise, the "one request but potentially many files" type of request carries a "jsonhtml=1" parameter.) From the insights I have gathered so far, I reckon the easiest way to permanently resolve the timing issue would be a modification on the client (Javascript) side. If one could have some sort of token/semaphore system to limit the number of upload request which can happen at the same time, this would effectively serialize the upload requests and thus resolve the issue of corrupted drag-and-drop attachment uploads. So the idea would be: Initially, there is exactly one "upload permission" token held by the main process. Each Javascript file upload requests needs to acquire this "upload permission" before doing anything. Once the first request takes this token, it may start its upload process, exclusively. Meanwhile, a second upload request could be waiting in the browser, but not proceed, because there is no further upload permission token. So the second upload will wait for the first one to finish, as the first upload returns the upload permission token upon completion to the main process, and the second uploads now seizes control of the token. And so on, until all uploads are completed. But like I said, unfortunately, I'm unable to implement such a mechanism in Javascript myself. Another way that I could think of to resolve this would be to combine the "several requests with one file each" into a single request that uploads several files, like is done when clicking the "Add Attachment" link. But I suppose that this kind of "request merging" is not possible, because that's probably what would have been implemented originally, would it be feasible. I think it's safe to assume that the current versatile way of the "imp/addAttachment" request is really there for a reason. i.e. because "request merging" is not possible in Javascript. Mon, 19 Apr 2021 16:27:53 +0000 https://bugs.horde.org/ticket/14811#t93902