Facing problem of network write error :timed out

Hi

I have installed serialmail . It is configured in crontab to push mails to another mail server. It was working properly earlier as expected. Now it is observed that when ever maildirsmtp is run , mails do not get pushed . I have tried this from command line also. 
The mail server to which i am pushing mails is available and smtp is also running on it.

I am getting following errors always:

serialsmtp: fatal: network write error: timed out
serialsmtp: fatal: network write error: timed out
serialsmtp: fatal: network write error: timed out
maildirserial: fatal: making no progress, giving up

Sometimes i get this error also "serialsmtp: fatal: network read error: timed out".

Right i am stucked with this problem. I am using another software sendqmailq temporarily for pushing mails.

I want to know if anyone observed this problem and also ways to eliminate this problem.

Thanks
Wilson