To you it, make a POST using the multipart/form-data content type on
/send-to/?email=<email-of-target-user>
Files are transmitted in the 'documents' fields of multipart/form-data body.
Each file must have a filename given in its content-disposition header.
Example:
POST /send-to/?email=john.doe@exampke.com HTTP/1.1
Host: localhost:8000
Content-Type: multipart/form-data; boundary=---------------------------9051914041544843365972754266
Content-Length: xxx
-----------------------------9051914041544843365972754266
Content-Disposition: form-data; name="documents"; filename="attachment1.txt"
Content-Type: text/plain
Content of a.txt.
-----------------------------9051914041544843365972754266
Content-Disposition: form-data; name="documents"; filename="attachment2.html"
Content-Type: text/html
<!DOCTYPE html><title>Content of a.html.</title>
-----------------------------9051914041544843365972754266--