I am trying with MS outlook 2003 from a Windows XP machine. I have another machine with Windows XP and Thunderbird as the client.

When I try to send a mail, it keeps waiting for long time and atlast gives me timeout error. This does not happen always. Sometimes it waits for a long time and then sends the mail. Sometimes it sends immediately when i click SEND.

The timeout messages are not recorded on the server as the smtp requests doesn't reach the server. The mails which take long to sent - I can c the logs recorded immediately once the server accepts the smtp request.

But after all these tweaks, I can see my server has got relaxed to a great extend. All these days it was under panic.

Ok, this is better information. It is easier for others to help if exact error messages are shown (copy/paste, or write the exact message you see in a dialog). Without this critical data, we're left guessing, and this makes it less likely anyone will actually help, or do so quickly and efficiently. Certainly there is more of a message than "timeout".

A frequent timeout culprit is mail scanning A/V software on the mail client's host. Are you running any A/V software on the Outlook machine that scans email?

Thanks for the support once again Mr.C.

I am using these forums for the first time and I am totally confused. Sorry for that. I understood that and from now I will detail everything.

I tried disabling the antivirus too, referring some other solution forums. And I am glad to see that the timeout error has not creeped in for so long after those tweaks. Once I get any timeout error I will update you.

No problem.

FYI: A/V mail scanning software must act as a proxy, intercepting mail from your client, and caching the entire contents to perform A/V scanning. Only after it has accepted the entire message and scanned it, does it pass it on to the mail server. It must be well behaved, but unfortunately, many (most?) are not. If your mail server is doing A/V scanning, there is little reason to also perform it on the desktop, especially at the expense of reliability. Just keep the junk disabled.

If you must enable it, be sure to increase the timeout period in Outlook's SMTP sending timeout period. Outlook expects to be able to send the message fairly quickly, but A/V mail scanning software in popular A/V products is very slow. Hence timeouts.

Ok buddy, I understood. Thank you so much for this support.
I am waiting for a time out error now to update you completely.

Meantime, shall i ask you some more doubts ?

1) My mail server is configured in such a way that it does not accept mails from proxy servers. But it even bounce back mails if the scenario is as described below.

Suppose a domain, say example.com hosted on 111.222.333.444 and the are using a mail server mail.example.com hosted on 444.555.666.777.
Mails sent by a user@example.com thru mail.example.com are also rejected(bounced back) by my server. I have some customers complaining about this.


2) Another configuration done on my server:

Out going mails thru my domain - mydomain.com are accepted only from the hosts listed in mynetworks. So if someone needs to configure a mail client from a host which is not listed in mynetworks, the problem comes up. If someone needs to configure clients as described above, they need a static ip which I should list in mynetworks. (This is done to lessen spam and attacks on my server. All these were done by my predecessor and I am following that) Is there anyway that I can allow everyone to configure their clients to send mails?

I hope you understood the situation and my queries.

For the second one, you can set up authentication (SASL) in conjunction with TLS (to avoid sending plain text passwords), and permit sasl authenticated senders. There are a number of howtos on the postfix site.

Hi, thanks you for the information. billymayday - I am sorry for not giving you the requested details earlier.

That's fine.

The terms "rejected" and "bounced" are two distinct states, and should not be confused.

Reject happens during the client-server SMTP conversation. The remote server does not accept the message, and informs the sending client of this fact via 4xx or 5xx reject reply codes.

Bounce happens after mail has been successfully accepted by the remote site and the remote site has indicated this success via a 250 OK reply code. The server that accepted the mail may find itself unable to deliver the mail, and hence must send a bounce notification to the envelope sender of the message. The envelope sender is trivially, and routinely bogus, and when forged, innocent victims receive the server's bounce messages. This is called backscatter.

With that out of the way, perhaps you can clarify your meaning of the above issue.

Ok. Sorry for the late reply.

Actually, mails sent by a user@example.com thru mail.example.com are bounced back by my server. As per my observation, it is because the domain server and the mail server are different hosts and treated as spam. This is only my doubt. The fact may be different.

I am not sure which entry in my main.cf is doing this. In fact, I am updating my main.cf entries.

There is no such thing as a "domain server"; perhaps you mean MX? Inbound (MX) and outbound (SMTP) mail servers are routinely on different hosts.

I don't understand the purpose if wild speculation when you have good data in your logs. That is always your primary source of debugging. Show such a log entry, and all related log entries for such a bounce. Start by finding the reject message, and then search for all log entries that contain the same queue ID.

If you have questions - show the log entries. Otherwise, we're dead in the water.

Can you help me enabling authentication while sending mails?

I will explain the problem :

Now I have a list of host IPs in my network list and those hosts are only permitted to send mails thru my server. Till now that was enough, as we had all our employees under 2 roofs and both those had static IPs. But now the things are changing and we have employees around the world. I have enabled squirellmail for them, but none is satisfied with its interface. So I would like to enable any email client on their machines. Now the hosts outside my network can only view incoming mails with mail clients like OE, MSO, Thunderbird etc. They are not permitted to send mails. So I thought of a solution and found that authenticating the outgoing server is a good option. But I am totally blind of the mechanism. I tried some HOWTOs on www.postfix.org, but couldn't get thru. Can anyone refer me a good tutorial or guide me in understanding the mechanism ?

Sorry to ask like this.

Order The Book of Postfix: http://www.postfix-book.com/ if you want a step-by-step procedure of setting up a mail server, including authentication (SMTP AUTH) and encryptiong (TLS). More importantly is that it explains how things work, and why you perform certain configuration steps. And it will always be an excellent reference.

Do they have valid usernames on your linux box?

Thanks a lot Mr.C. I will try the book you suggested.

billymayday - All the users have valid usernames, as they can send mails thru squirrelmail. I have blocked everyone except the ones on mynetwork, in sending mails thru my server. The entry in main.cf is doing this for me (I am not sure of the entry which is doing this).