Trouble shooting pppd connection

[Linda]

I occasionally use pppd to connect via dialup and view mail 
on our imap server but since I moved to 12.04 LTS it isn't 
working properly.  I'm not sure where to start to trouble 
shoot so if anyone can suggest how to start trouble shooting 
this I would really appreciate it
Here is what I have set up and what is happening:
I have pppd working for dialing in the machine answers the 
phone and on login starts pppd
I do: route add dailin-machine-ip-address ppp0
I do: route add imap-machine-ip-address ppp0
I have static ip addresses assigned in /etc/ppp/options.ttyS0
I turned on IP forwarding    echo 1> 
/proc/sys/net/ipv4/ip_forward   and changed /etc/sysctl.conf 
so it will turn on by default at boot
Once I have logged on and have pppd started when thnuderbird 
tries and pick up mail from the imap server it times out
  I can type ssh dialin-machine-name for the machine I 
logged into connect no problem however if I type ssh 
imap-server-name ssh times out.  Any ideas on what I am 
missing that causes the connections to time out?
                                  Thanks
                                  Linda