I'm having troble using Microsoft Outlook behind IPCop.
When trying to send emails via smtp I get a respond that timeout exceeded, error code 421. My ISP tells me they don't have any disturbances on the service, so I figure it must be my firewall or something with it.
Receiving mail via pop is working fine, but not sending through smtp.
In its default configuration, IPCOP does not block any outgoing ports, unless you or someone else has enabled filtering of outgoing connections.
In addition, POP works so port 110 must be enabled for outgoing connections.
Looking up error 421 from the list of SMTP error it says:
421 - The service is not available and the connection will be closed
This definitely means that you got through to their server but was refused a connection, so it's not to do with your firewall. If it happens once in a while it's OK, but if you can't get through at all I think you'll have to take it up with your ISP.
Maybe they require you to enter authentication details like a user name/password.
By the way, has it ever worked? Or did it stop working after you changed something?
I am having a similar problem with Outlook and Zone Alarm Pro. On my desktop PC, which is my direct internet connection, can receive and send emails but on my networked laptops, which share the desktops internet connection, it will receive but not send giving me the same timeout message mentioned earlier. I am pretty much a newcomer to firewalls but imagine it's a throughput problem with my setup that it meeds to be setup somehow to allow passage of outgoing traffic across my network.