i am trying to use my mail server when my 25 stop but its not working.
for example my ip block 192.168.2.5/29 and my mail server ip 192.168.2.6 same ip block no problem when my client use 192.168.2.10/29 than SMTP not working and i open 25 port than my ip block by smaphaus. any one solved this problem. i am using routerbord 1200.
Spamhaus blocks not only spammer sites, but residential ip groups. If your public ip is determined to be not commercial (like issued by dhcp), then email servers that use spamhaus to block spam will block you.
The solution is to get a static ip from your provider, or if your ip is commercial, see if you can get spamhaus to lift the block on your ip subnet.