Ok, as I don't like uninformed guesses about whether something works or not, I tried it.
I changed my time zone from UTC+1 to UTC+9 at about 6:30 pm so that the time changed to 2:30 am of the next day. Then I rebooted and checked whether I would get notifications for e-mails I sent to myself.
I didn't.
Once I switched the time zone back to UTC+1 and restarted account-polld, I received notifications for all the messages that weren't shown before.
In my opinion this shows that we should use the previous solution using the 1d parameter.
Ok, as I don't like uninformed guesses about whether something works or not, I tried it.
I changed my time zone from UTC+1 to UTC+9 at about 6:30 pm so that the time changed to 2:30 am of the next day. Then I rebooted and checked whether I would get notifications for e-mails I sent to myself.
I didn't.
Once I switched the time zone back to UTC+1 and restarted account-polld, I received notifications for all the messages that weren't shown before.
In my opinion this shows that we should use the previous solution using the 1d parameter.