I just got an email with the title "New kobo questions for Nov 24 - Stack Exchange". Hooray! But when I followed the link to the question I noticed that it was asked 10 days earlier (modulo timezones) - on the 14th of November. The question has not been edited since its conception.
In my subscription overview I can see that I have a daily subscription on that tag: Emailing every day to...
From the email header it seems like it was actually sent that late by an internal Stack Exchange server, so it has not been delayed on the way to my server:
Received: from [10.7.2.16] (helo=[10.7.2.104]) by mx-out.stackexchange.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91) (envelope-from ) id 1gQNh7-0007y2-Pj for email@example.com; Sat, 24 Nov 2018 02:29:17 +0000
... and a second later, my mailserver received it:
Received: from mx-out.stackexchange.com (mx-out.stackexchange.com. [220.127.116.11]) by mx.google.com with ESMTPS id t6si19417407qkd.163.2018.11.23.18.29.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 Nov 2018 18:29:18 -0800 (PST)
Is this expected?
PS I originally mis-posted this question to meta.stackoverflow instead of meta.stackexchange.