Block port 25 or SMTP port for non replay LAN IPs

Do a Blackhole NAT rule. See: https://doc.sophos.com/nsg/sophos-firewall/19.5/Help/en-us/webhelp/onlinehelp/AdministratorHelp/RulesAndPolicies/FirewallRules/FirewallRulesBlackHoleDNATRuleCreate/index.html

Adapt it to your needs. If you want to restrict it from LAN, then check The Port of LAN instead. 

but Its block All Traffic I just want to allow smtp Traffic on some allowed terminal and block other terminals.

Then you can make a rule to allow SMTP traffic for the specific clients that are allowed in the source addresses followed by a rule to block all SMTP traffic. Then only the allowed clients can use SMTP and all others are blocked. If it's internal clients you would like to block, you can also use reject instead of drop, so the client gets a message back that traffic is not allowed. From WAN drop is the better choice.

Then you can make a rule to allow SMTP traffic for the specific clients that are allowed in the source addresses followed by a rule to block all SMTP traffic. Then only the allowed clients can use SMTP and all others are blocked. If it's internal clients you would like to block, you can also use reject instead of drop, so the client gets a message back that traffic is not allowed. From WAN drop is the better choice.