Well we have another addres which is 198.30.63.65 but when we this one as nat pool when people send mails , it prompts that there is no reverse DNS
Then try using the 198.30.63.65 for the static map. To be honist, I'm not sure that this will solve it, but give it a shot. I'd do the following in sequence:
1. Remove the line:
ip nat inside source static 192.168.2.24 198.30.63.64
2. Add the line:
ip nat inside source static 192.168.2.24 198.30.63.65
3. Clear your IP nat translations, and wait..... See if it happens again.
If the above does not solve it, then I'd try the following:
1. Prepare to take your network into a temporary maintenance period. Say at midnight, or when no one is using it.
2. Now, remove all the following lines:
[code:1]ip nat inside source static tcp 192.168.2.199 25 198.30.63.64 25 extendable
ip nat inside source static tcp 192.168.2.23 80 198.30.63.64 80 extendable
ip nat inside source static tcp 192.168.2.23 110 198.30.63.64 110 extendable
ip nat inside source static tcp 192.168.2.23 1352 198.30.63.64 1352 extendable
ip nat inside source static 192.168.2.24 198.30.63.64[/code:1]
This is will remove all static NAT, only dynamic NAT remains.
3. Clear your IP nat translations, and wait. Use your network normally by sending and receiving mail to force the problem to appear.
4. If the problem does NOT appears then you know for sure the problem is caused by one of those lines you removed. Now add the lines one by one, while waiting/using the network for enough time after each addition. Once the problem appears, you will know exactly which line is causing it. Tell us about that for further analysis.
5. However, If the problem does appear even after removing all the above lines, then I'm really not sure what is it, but at least you know that there is nothing wrong with those lines. Tell us in this case and we'll try to help.
