All the sudden (not quite, did some "housekeeping" work over the WE, including replacing expired certs - most probably broke something in so doing) I have one of ur exchge server 2013 (latest CU) no delivering messages to mailboxes
The messages are adopted from remote servers but stuck in the SMTP delivery queue (yes it is a french UI)
The error message reported is:
11.04.2020 21:32:02 - Remote Server at maildb01 (192.168.168.2) returned '441 4.4.1 Error encountered while communicating with primary target IP address: "Failed to connect. Winsock error code: 10061, Win32 error code: 10061." Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts. The last endpoint attempted was 192.168.168.2:475'