How come I can't send e-mail but I can receive it?

For three days I have not been able to send mail. I have done all the trouble shooting I can think of and find. I use Incredimail and it states "server cannot be found, try again". I went through all the "help" and nothing works.

It's some weird firewall thing. If there's some form of web-client, you'll be able to send through that. I see this commonly at schools and hotels, etc... It just seems to block software email clients from sending outgoing mail. If you know what you're doing, you might want to try resetting your network.