Ideally it would work like this:
- The activity summary would be sent with the periodicity set in the user preferences (default: weekly).
- It would not include any content the user has seen (therefore no posts authored by the own user either).
- Next items in queue would be shown instead.
- Instead of “Since your last visit”, the summary header would say “Suggested reading” or something along these lines.
- In the Activity Summary, section of the user preferences, a new checkbox would read “Send me the email summary every week regardless of my visits.” or something along these lines.