Why does this forum gets overloaded with error 503 every time email digest is sent?
It’s hard to say. I occasionally see that, but normally reloading a minute or two later, it will go away. I had never correlated it with the email digest (but I don’t have the forum emailing me the digest anyway, which would make it hard to correlate).
Since the NodeBB group is kindly freely donating the webserver space for this Notepad++ Community forum, it doesn’t bother me if every once in a while, there is a brief time when navigating here gives a 503 error.