I have 2 companies on the same T1 line, they each have their own domain name and win2k3 sbs servers hosting email separately. Sometimes, email does not get delivered to the other server and times out, sometimes it works perfect. no rhyme or reason. Scenario:
server1 is connected to a pix501 with public ip of 184.108.40.206 and domain is domain1.com.
server2 is connected to a pix501 with public ip of 220.127.116.11 and domain is domain2.com.
The T1 has 5 ips and uses a cisco 1720 as it's router with ip 18.104.22.168 which is the gateway for both pix's.
If a user from domain1.com sends an email to a user on domain2.com, the message will sit in the exchange queue until it times out. If the same user sends the message again the next day, it gets delivered to the other server in milliseconds.
Neither server has any trouble sending email to any other domains. If it was consistent, I would say that the 1720 could not send the traffic out and receive it back in to the other IP, but it is very sporatic. Short of setting up a vpn between the pix 501s, does anyone have any ideas on how to make this work?