permit the user to point the location of one or more photos
with non-geotagged photos, a map could be shown with a fixed marker in its center.
Any user could suggest the geoposition of this photo (or of a group of photos) simply pinching in/out and dragging the map until the central marker is in the point where the photo was shot.
https://stackoverflow.com/questions/39753364/how-to-fix-marker-in-center-of-leaflet-map-after-user-will-drag-the-map helps to make the fixed central marker.
The position could be communicated emailing the photo name with complete path and its latitude and longitude; the exiftool command that modifies the photo could be added as well. Javascript isn't aware of the filesystem path, so in order to insert it in the mail a php trick has to be used.
Edited by Paolo Benvenuto