115200bit/s, 8 data bits, 1 stop bit, no parity, flow control=none by default. Baud: 115200 Data: 8 Parity: none Stop: 1 Flow: none
Drop port 25 abusers/beyond X connections/X packets/sec without 1d timeout
/ip firewall filter add chain=forward protocol=tcp dst-port=25 src-address-list=spammer action=drop comment="BLOCK SPAMMERS OR INFECTED USERS" add chain=forward protocol=tcp dst-port=25 connection-limit=30,32 action=add-src-to-address-list address-list=spammer address-list-timeout=1d comment="Detect and add-list SMTP virus or spammers"
Note: You'll need to setup the limit & burst for the rule manually, once the rule is added.