SMTP problem - URGENT

[leigh]

I have a client who cannot send out emails through our mail server; they are receiving fine, just not being able to send. They are using Outlook on port-25. They have used the AutoConfig in CPanel, but it still won't work right. It has been working fine for months now, up until yesterday. And now none of this company's email accounts will send out all of a sudden. We have changed his SMTP port on his pc to port-21, but is still getting an error message (10060 No Socket Error Message). I had a customer yesterday with the same problem, and we had to switch his SMTP mail server over to his ISP to get it to work. They can send out email from webmail, just not from their Outlook. And this is for everyone in their company. Any help? I've searched the forums, but to no avail. Am running WHM 9.9.8-CPanel 9.9.8-R160, RedHat Enterprise 3-i686. Thanks!!!

[AndyReed]

I need to know the complete error message they get when trying to send out email message using Outlook Express.

[mahinder]

We have changed his SMTP port on his pc to port-21
>>>>>>>

port 21 is ftp port and is not SMTP port. i think their isp is blocking port 25 hence they are not able to send out emails. login to whm click service manager and check
exim on another port and run it on another port example port 26. now tell client to use port 26 by checking advance option of accounts and your client should be able to send emails fine.

[leigh]

Here is the error message:
The connection to the server has failed. Account: 'xxx@xxx.com', Server: 'mail.xxx.com', Protocol: SMTP, Port: 25, Secure(SSL); No, Socket Error 10060, Error Number: 0x800CCC0E.

I also received this from them as well:
===
Leigh,
As you probably already know, we can not send outgoing mail. I have checked to make sure that all ports and related information in OE are correct. The problem stems from the previous problem that was not addressed, where our mail server was being used to send malicious and bulk mails by outside users. Now I suspect the problem is that since there were so many malicious mailings being routed through our domain, your ISP has put a block on our port 25 transactions (this is pretty common with some ISPs). One workaround is to change our smtp port to 26 instead. I have run a port scan on your mx (cp1.ellisgs.com) that also shows that port 25 is blocked from us while you are only accepting data on IMAP (port 143) and POP3 (110) TCP ports. I have also tried to telnet to port 25 on our mail server and yours and it only results in a timeout, while any other resolves fine. To me this only proves that your ISP has a block on port 25 transactions from either our local address (68.95.141.239) or our IP that you are hosting (69.93.115.33).
Please let us know what you can do to address this....
===========

[leigh]

We have changed his SMTP port on his pc to port-21
>>>>>>>
now tell client to use port 26 by checking advance option of accounts and your client should be able to send emails fine.

I have sent this along to him, an am waiting a response. Hopefully this will work.

[leigh]

Just got this back from the client:
=====
We tried changing to port 26 and that still does not work. So that means to me that there may not be a block from your ISP. It could be that the SPF records you created dont reflect our current IP (if you have specified an ip4 entry in the first place). We use DSL and our IP changes every once in a while. The old ip was 68.95.129.46 and now the new one is 68.95.141.239. Our ISP COULD be blocking us, but im not sure that they would also block port 26. Also, I can telnet and connect to other mail servers on port 25 - so i doubt that is the case.
========
Now what???

[sawbuck]

Do you a SPF entry and if so what is it? Seems unlikely that is the problem.

[leigh]

iptables and APF were stopped. When this happened, my customers were both sending AND receiving emails fine. Not sure why though.

[dezignguy]

you must not have the appropriate incoming ports added to the conf.apf config file for apf.

[brianoz]

I get this happening all the time. ISPs love to block port 25 as it just rules for them - it cuts out spam originating on their network, and it stops most worms dead in their tracks. And they rarely, if ever, actually tell customers before they turn the block on.

Get the customer to test the port with the following command from a DOS window:

telnet hostname 25

If that times out or fails then that tells you immediately that the ISP has blocked port 25. I wouldn't use port 21 as an alternative by the way, it's already taken!! Use port 26 or another, higher port (doesn't matter too much). And as someone has mentioned don't forget to add it to APF! Test the port from outside your machine yourself with the telnet test I gave above so you can be sure it works. Or go to http://dnstools.com and use the open port tester there to check that the port actually is really open. If you can open the port from outside and they can't it's a problem at their end.

Cheers!

[dezignguy]

Well, he said that when APF/iptables was stopped, then mail was able to go both ways. So It must not be the isp then, it must be his firewall not being configured to allow that port through.

[brianoz]

D'oh - yes, I agree, I misread that!

- Brian

[leigh]

Seemed it was his ISP. Port 25 and port 26 are both open in APF. But APF is still stopped and no one (yet) is having problems (I have over 75 accounts). When he changed over to his ISP's SMTP server, all was fine as well.