> Please let me know what could be the issue. [...]

   Based on what?  Junk like "servername2.example.com" or "10.XXX.XX.0"
conveys no useful information.

> I am getting "No route to host" error while trying this.

   I'd guess that that's because there's no route from "10.XXX.XX.XX" to
"10.XXX.XX.XX", but, with my weak psychic powers, there's no way for me
to know.

> mynetworks = 10.XXX.XX.0/28, 127.0.0.0/8

   "/28" doesn't leave very many possibilities, but, again, I have no
idea what you're actually doing, so I'm stymied.

> telnet is disabled and hence I cannot try telnet <remote host> 25.

   Did you try it?  (Naturally, I have no idea what "telnet is disabled"
means to you.)  "I cannot try"?  Really?  Your fingers don't seem to be
broken.


   Please include some useful information when posing a question like
this.  Note that addresses in the "10.*.*.*" range convey no secret
information which might be useful to anyone outside your network, so
there's no good reason to hide them.  For example, the system I'm on now
has address 10.0.0.9.  Knowing that, can _you_ get to it?  Hiding
harmless, important data simply wastes everyone's time.