This is an add-on to be used with Mozilla Thunderbird e-mail program.
It can be installed from Thunderbird's add-ons section, or from the Mozilla add-ons website:
https://addons.mozilla.org/en-US/firefox/addon/filerun-for-filelink/
This add-on allows you to easily e-mail large file attachments by uploading those attachments to your FileRun user account and then inserting a web link to the file into the body of your email.
The add-on will not require you to share your FileRun username and password with Thunderbird, but instead it leverages FileRun's OAuth2 server to authorize Thunderbird to perform limited operations on behalf of your FileRun account.
Files uploaded to FileRun through this add-on will be located inside the automatically created folder "Apps/Thunderbird".