Problems receiving mail from external mailserver

[thejonmoore]

I have looked over this forum, and found several things close, but nothing that addresses this issues in a helpful manner.

Zimbra is running, and working just fine. The only problem is receiving mail from external mail servers. I can send and receive fine internally, and send find externally. When a user sends an email from an external account (yahoo.com, gmail.com, etc) they get a bounce back saying the message could not be delivered.

We are using a spam filtering system with our ISP. All mail sent to your domian is first sent to their mail server (mail.isp.com) and then passed on to ours. The error comes up when their mail server (mail.isp.com) tries and handoff the mail to us.

I have spoken with the ISP on this, and they are saying that my mail server (zimbra I assume?) is refusing to accept the mail from their mail server.

My question:
How do I setup Zimbra to accept incoming mail from their mail server?

Thanks for any help.

[bobby]

have you looked in /var/log/zimbra.log to see what postfix says when it bounces their deliveries? to what domain(s) are the inbound messages destined? are those domains provisioned in zimbra (zmprov gad)?

[bobby]

assuming your server is behind a firewall, is it forwarding inbound traffic on port 25 to the server? does the machine itself have the firewall in effect (iptables --list)?

[thejonmoore]

Bobby,
Im not at the server right now, so i can't post logs, but if needed i will when i return to that location. as far as the questions, to my understanding the mail is arriving at the zimbra mail server, and is being rejected because its from an unknown sender. (what im getting from the ISP is: my mail server isn't allowing mail.isp.com to delivar mail for @mydomain.com)

Zimbra is setup for my domian, the firewall is fowarded and all. I can telnet to the mail server on port 25 and "hand deliver" a message just fine. When i receive mail from zimbra on an external address, such as my personal yahoo mail, the message headers indicate its comming from my mail server from the correct user. The only problem with the setup, from what i can figure out, is that the postfix inside Zimbra isn;t letting the ISP email forward/relay/ mail to the zimbra server.

As you can tell, I don't know much about email, if i made any errors in the syntax of things let me know.

[jholder]

Hi,
Out of curiosity, what makes you think the mail is getting to the server?

[thejonmoore]

Hi,
Out of curiosity, what makes you think the mail is getting to the server?

I receive a message from the ISP's mail server saying

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

 an undisclosed address
   (generated from administrator@XXX.com)

I talked with the email guys at the ISP, and they checked their logs. They are saying the message is getting to their email system its doing the scrubbing/scanning/whatever and then attempts to hand it off to our email server, at this point, the connection is refused. What I am getting from them is along the lines of "when 'we' try and pass the mail to 'you' your mail server is refusing because 'you' don't accept relayed messages".

I only understand about 60% of what they are telling me. I will be happy to provide as much information as is needed, but I am not sure what you guys will need, so just ask. Thanks.

Also, I have been reading on the postfix website, (which is the email server Zimbra uses, correct?) in the docs, it talks about the $relayhost parameter. Would adding their mail server name to this parameter solve this problem? Or am I on the wrong thing again?

Thanks for the help.

[bobby]

have you looked in /var/log/zimbra.log to see what postfix says when it bounces their deliveries? to what domain(s) are the inbound messages destined? are those domains provisioned in zimbra (zmprov gad)?

hmm "the connection is refused" is different from "not accepting relayed messages" though you already mentioned "I can telnet to the mail server on port 25 and hand deliver a message just fine". as long as that means from outside the network

definitely should see what postfix is saying in /var/log/zimbra.log

reading up on postfix is a great idea (i do it myself sometimes ). you'll notice a number of postfix parameters are configurable through the zimbra admin console, including relayhost, though it is used for outgoing mail so is outside our scope for this problem

[thejonmoore]

have you looked in /var/log/zimbra.log to see what postfix says when it bounces their deliveries? to what domain(s) are the inbound messages destined? are those domains provisioned in zimbra (zmprov gad)?

hmm "the connection is refused" is different from "not accepting relayed messages" though you already mentioned "I can telnet to the mail server on port 25 and hand deliver a message just fine". as long as that means from outside the network

definitely should see what postfix is saying in /var/log/zimbra.log

reading up on postfix is a great idea (i do it myself sometimes ). you'll notice a number of postfix parameters are configurable through the zimbra admin console, including relayhost, though it is used for outgoing mail so is outside our scope for this problem

I will check those logs, any other places you know that might have any needed information in it?

Yes, I can telnet from outside our network. I have setup zimbra to serve mail for our domain name. We have all the appropriate records and such for email setup on the public DNS server, etc. I am sure that email in general works, as we have a Exchange server that has been running for several years, and it works great*.

Most of the information I am finding here, and elsewhere on the net, addresses the reverse of this problem. They can receive but can't send mail.

Just an idea, the outside mail servers are simply doing spam filters and virus filtering, i noticed Zimbra supports spam filtering. As a possible solution to this problem, would just disableing this server from our ISP and doing the virus/spam interneal allow things to flow more smoothly?

[KevinH]

Run a test and post the results from /var/log/zimbra.log