thanks for quick reply
1. yes it is new installed server,
2. I am not able to send mail through telnet 25 i am getting an error as "sender address rejected: not logged in
3. No we have not changed any thing in intranet, we have 1 server where iredmail in installed & 3 client desktop's all are connected to the router using static ip.
Note : one more thing is I am able to send / receive using a blackberry mobile phone