Attachment confusion - .pdf/.crdownload

Copper Contributor

I've got a quandary with one user who is attaching a .pdf to an email, using the "Attach File" menu, but when the file is attached and sent/delivered, the attachment has been renamed with a .crdownload postpended (i.e., changing the file's type).  So, email now has "somefile.pdf.crdownload" attached rather than the original file of "somefile.pdf".

Any idea what's causing this oddity?  The attached file was recently downloaded from another system, but clearly shows the filename as ending in .pdf.  The impact is that recipients get the, perhaps unknown filetype, unless the .crdownload has been previously associated with an application (Acrobat Reader in our case).


Thanks for any guidance or suggestions!


Edited to clarify that this is Windows 10 environment with installed MS 365 apps.

1 Reply

Hello @keithmiller0,

the .crdownload extension is typically associated with Chrome and indicates a file that is still in the process of being downloaded. If the file is showing up with this extension when attached to an email, it suggests that the file may not have been fully downloaded.

If you start a download in the Google Chrome web browser, Chrome appends the extension "crdownlaod" during the download process. As soon as the download is complete, Google Chrome removes the extension again. If you cancel a download, Chrome automatically deletes these files. However, if the browser or operating system crashes, the file with the extension "crdownload" remains on your computer.

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