Use command:

   /ip dhcp-server lease print file=lease detail
   

Or can use “terse” option instead of “detail”. Using “detail” will include information on the static allocations. Result is

Paste is not supported for web terminal, but using SSH can enter e.g.

   /ip firewall filter add action=accept chain=forward dst-address=52.208.184.61 dst-port=587 protocol=tcp

Documented here

Unifi L3 Adoption with DHCP Option 43

Need to use an extra parameter, recent Linux restricts SSH options. Example:

   ssh -oHostKeyAlgorithms=+ssh-dss root@10.3.76.115