@Sumit_Arora and others
I faced the same issue after migrating my local virtual machine to a remote server. The setup that i was using worked fine for the VM on my local machine, but did not work for the remote server.
I fixed this by setting the host_name Property in banch/sites/[erpnextfolder]/site_config.json to the appropriate value, since I changed this value to make the PDF generation work for outgoing mails (see PDF Email Problems Thread - #31 by s.ilter) on my VM.
{
...
"host_name": "[http(s)://your.host.name or http(s)://your.host.ip.address]",
...
}
}
This certainly worked in my case.
Hope this helps.