Issue with files located on a very long file directory route

[zenzen]

@OttoAcuna

if I copy or move those files into the Downloads directory, and re-attach them, then I get no issue and the email is sent well.

This makes me think the issue is not with the length of the filename but with the package format used. Please open a terminal and run the command:

flatpak list

If you see Thunderbird listed in the output, the cause of your issue has to do with how it was installed. Please see these related threads:

Thunderbird attachment drag and drop not working

Before you do anything I'm curious if you can drag and drop files located in your Downloads folder, as this is one particular directory usually available for flatpaks by default. If files from this location work, but not from any other, then you have a good indication that flatpak permissions is the problem. If it doesn't, well, it could still be a permission issue but it simply doesn't allow access to the Downloads directory either. But it's a very quick and test, and could help with troubles…

Issues with saving multiple attachments in Evolution email client

This may be the issue. Packages installed through Flathub (known as flatpaks) have restricted permissions by default so that they cannot access the filesystem freely. If going with the preinstalled version of Evolution is not an option (which would mean downgrading to 3.4.4), then I suggest you install Flatseal from the Software Store and give the necessary permissions to Evolution: [sc1] Add a new entry as shown; xdg-run is short for /run/user/<user_id> which should grant permission to that…

Possible solutions are:

1. Uninstall Thunderbird and re-install it again using the .deb package format, which you can identify by the "sources" drop-down under the blue install button; it should say "Zorin OS".

2. Install another program called Flatseal to grant unrestricted file system access to the Thunderbird Flatpak.