Hello,
i have investigated today a weird issue of one of our clients, that did not received messages sent from another user from Office 365.
In the log i have found that messages was blocked by ESF:
2018-03-21 10:19:01 1eyZtd-0009DX-PY H=dev.xxxx.com (web1.xxxx.com) [xxx.xxx.xxx.201] Warning...