User-friendly sites have a Preferences button for managing
subscriptions, etc. I could find no such option here.
I did discover what appears to be a quick and easy way to change your
subscription preference to Daily Summary (i.e. only 1 email per day):
Click on "Unsubscribe" at the bottom of the digest (or individual
message, I presume). This opens a page with several options. Select
"Switch to Daily Summary". I hope this works. Not very intuitive, but
I had a feeling that if I "threatened" to unsubscribe, I might be
offered other options!
Oops, I just received another digest! Does this mean that my request
for one per day did not take effect? I'll see what happens tomorrow.