OK. First, I am very new to ISA Server, but even worse on Linux firewalls. So please bear with me. If I do not provide enough info please let me know.
I have two firewalls. One ISA and one Linux. The Linux firewall is old, not up to date, and we just plain do not want it anymore.
My issue is that when the two firewalls are up everything works fine. Email, Web, Our published web server, Vpn....and so on. When the Linux firewall is down everything still works fine.....for a while.
Today I shutdaown the Linux server around lunch time. I went around and evryone was able to send and receive email. I was happy! After a couple of hours I started receiving phone calls. One by one people were unable to send and receive email. After five people calling me I started the Linux server back up and everything was fine. I don't understand why some people were able to send/receive and others were not. All machines are setup exactly the same.
By the way the error I am receiving for Outlook when they do not work is "The specified server was found, but could not get a response." Does this sound like a packet filter problem? If so I have one set for Incoming Pop Protocol.
Any help is appreciated,