Zammad 6.5.2 on Ubuntu (package)
When customer creates new ticket, Zammad send notifications to all agents via SMTP to MS EoL.
We notices some instances, when instead 5-6 e-mails EoL shows only 1 received notification.
Copilot based on provided info happily confirms, what highly-likely MS side silently drops other notifications due to some internal bulk-send protection.
This problem is not easy to track, it is very unstable. Zammad logs may show some errors only when set at debug level, what is not a every day operation mode for logging.
So, please, add some small delay (10-20 mS) between e-mails, what Zammad send via SMTP.
Or add some option to confirure such delay.