Once more for luck, squid in a web proxy, not an imap / pop3 proxy. Please read up on these subjects.

Yeah I understand that squid is web proxy and not imap or pop proxy. But that is all the issue. I do not want to intercept the email data. Nor do I intend to in the future. But because our squid is so placed in the network that all the data has to pass through it. Right now as squid is transparently doing it, the email clients do not need to worry about it. There is a setting in thunderbird preferences where I can set it for proxy settings, but it is not working. It seems I need to use squid as socks proxy as well.

squid is NOT a socks proxy. *ALL* traffic can *NOT* pass through squid.

Ok. Then what is the better way of doing it. Any other option or any add on or anything? Plugin for squid?

christ, you've no idea what you're doing have you??

I have. I remember some time back in a similar setup evolution worked quite fine. But not thunderbird. I am not trying to proxy pop and smtp requests. Neither do I intend to.

Maybe what I am looking for is Delegate. One of the members here had a same issue and some one suggested delegate which can be used as an application level proxy for multiple protocols. Will try it for pop and smtp and squid for http.

If, and this is a big if, your email client AND server can be configured to use an http proxy, it will work. Generally speaking however, the http proxy you feed your email client is only used to load http content, _not_ to send and receive email.

Otherwise, you need another proxy server, specifically a socks proxy. There used to be lots of free nifty socks proxy servers for windows 95/98, and linux clients and software connected to them just fine. Other than saying, you need a socks proxy, I can't help much, since the windows 95/98 days were the last in which I had to use a socks proxy.

Good luck.

I am back to square one. With the above script, I can not access the local addresses. And I understand that squid is http proxy and can not be used to send emails and download them with pop. And I have been trying to tell this to Chris as well.
As you said, I need socks proxy and I have one. I installed DeleGate, and it works fine. But another issue with it. It completely borks wpad. With delegate installed and running, browsers CAN NOT automatically detect proxy settings.
Also it is important that local addresses work as everyone here works with visual studio.

Well in that case it seems you do not understand your product choice well enough. If there are two proxies configured correctly and running independently then they will not interfere with one another. You are clearly doing something wrong without going in to nearly enough detail about it.

Yes. And that is where I need help. I have not worked with delegate before. And I thought delegate should be working independently and should not affect my current setup. And to extent it is not. It is just creating issues when browser is set to detect proxy settings automatically. If I configure browser for proxy manually it will work fine. But then I can not go and configure every browser on every machine. And wpad seems the solution for this.
Will still keep on reading on delegate even more.
Thanks for sharing my headache.

Ok. For my issues with email clients I have downloaded p3scan. It says it is a pop and smtp proxy which can work transparently. I downloaded and installed it from the source. It is available for download at sourceforge. The version I am using is 2.3.2.
Everything is fine but it does not seem to work. README file says I need to redirect pop and smtp ports to 8110, the default on which p3scan listens. And it is listening. lsof command says so.

I am using these iptables rules for transparent redirecting smtp and pop to p3scan.

But the rules are not working. And if I masquerade the output interface all the squid rules become useless.

Got email clients to work with p3scan. Only one thing that I am not able to get of of is right now is the wpad script with Firefox. It is working with IE though. So I guess the function isInNet is not going well with Firefox.

Ok let me put the solution in brief. Just install p3scan and configure its configuration file /etc/p3scan/p3scan.conf.
Start the p3scan. And put these iptables rules for transparent redirection so that email clients do not know about it.

Those two iptables rules have nothing to do with each other. first you redirect a tcp connection and then nat it? that makes no sense - that connection will never hit POSTROUTING.

Well, I was completely wrong. Nothing is working now. Everything has gone haywire.
But what I want to work out is those REDIRECT rules. I think p3sense is what I want but those redirect rules are not working. And I want them to work.
I am lost. Its Saturday, at 1800 and still at office. Nothing working out and my brain is completely out and need to get a coffee.