Hi there,

could you check your webserver and PHP error logs to see if something is in there?

Also could you enable the logging to a file in Matomo see https://matomo.org/faq/troubleshooting/faq_115/
You want to add log_writers[] = file to the [log] section basically and then see in the log file in the tmp/logs/matomo.log file within Matomo if there's any error in there when it didn't send an expected mail.

Hi,

thanks. I've enabled it and will report back in about a month, when the next reports are sent.
Is log_level = WARN sufficient?

Hi,

Please also take a look at #14467.

Since Matomo 3.10 there is an included command you can use to quickly send a test mail exactly the way the scheduled report would be sent.
Just keep in mind to use the same php as used in the cronjob.

sudo -u www-data php console core:test-email test@example.com

Hi,

the reports for October were all sent.
We moved our database to an SSD in the meantime, so maybe that fixed it (archiving is much faster now).
Maybe, also the latest Matomo update (3.12.0) influenced that, as there were changes to the archiving process?

If you want, to can close this issue.
If it occurs again, I'll write here.

Awesome 👍 feel free to comment again.