We discovered today that the mail notification stopped working on our OpenProject 8.1.0 installation. Wenn I go to Administration and send a test mail, this is send out. But assigning a task or creating one or creating a comment is not triggering a mail notification to the repective user. This was working when I updated the system to 8.1.0 in January. So I wonder what changed. Since we did not touch the config since then anymore. Because sending a test mail is working, I assume the the sendmail configuration is also correct. I also checked the production.log, but it is not completely clear to me if a sendmail command is really logged there or not.