Finally got back in after I found this thread... insane
http://forums.mozillazine.org/viewtopic ... &t=3041221
File link is an alternative to say WeTransfer/Hightail/Box etc using 'DL' DownLoad Ticket Service
https://github.com/DownloadTicketService/dl
It is extremely useful when you have slow uplinks and/or the sender or receiver has email attachment size limits to contend with.
It allows you to upload a file to a remote DL store and then put a link in the body of the email for the receiver. They can then click the link to download the attachment from your DL store.
In the event you are being asked to receive a large file, which your own provider may limit you receiving or the remote sender may be prevented from sending, you can send the remote sender an 'Upload Grant' which allows them to upload a file via a browser to your store, which in turn notifies you when the file is there and allows you to click and download via a link.
Due to GDPR etc etc we prefer to keep files on our own servers.
The plugin integrates all this into Thunderbird. Yes, we can manually add links via the DL frontend, but then you might as well just use a browser for your mail or another mail client.