I'm doing this now, manually, or at least trying to. Every time I send an email to my fiancee, I will, at the bottom, post the date sent and number of emails currently for that day. This way if any emails do not make it to her, she can see that something wasn't received. What this might look like:
Sunday August 2, 2026 3 Emails
Tuesday August 4, 2026 1 Email
Wednesday Aug 5, 2026 1 Email
Thursday August 6, 2026, 1 Email
Saturday August 8, 2026 4 Emails
Tuesday August 11, 2026 2 Emails 
Monday, August 17, 2026 1 Email 
Wednesday August 19, 2026 1 Email 
Sunday August 23, 2026 1 Email
It would roll up in September and look like this:
August 2026 16 Emails total
Tuesday, September 1, 2026 2 emails
Thursday September 3, 2026 1 email
This feature could be turned off or turned on for each individual, as you might not want this for everyone, or anyone.