Sending Email using a WCF service

Hi all,

I am trying to send email on update event of an entity, now plugin registered on that event 

calls the sendemail function in a WCF service. 

What i get is an error :

System.Net.Mail.SmtpException: Failure sending mail. ----> System.Net.WebException: Unable to connect to the remote server ----> System.Net.Sockets.SocketException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond XX.YY.ZZ.55:25
at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress).

Note: I can send emails consuming this service using Console Application  as a client in my local environment.

Any help/Suggestions would be highly appreciated, it's been long time trying to fix this issue. 

Regards

Prem Prakash