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Papi_Linux_Server 08-26-2011 09:23 AM

Mail server won't doesn't receive mails from external accounts

I have successfully configured an email server. The server can send and receive mails locally and it can also send to external accounts. The problem is, it won't receive any mails from external account. The is already an existing email server for this company i work for. I am creating another one for them. The possible problem is the mx record. how do i set mx record so they won't clash with the mail server that already exists? I am in South Africa and the email server that exists is in Belgium.

wpeckham 08-26-2011 10:27 AM

External mail
1. You can have multiple MX records for a domain, as long as they have different IP addresses. There is also a priority in the record, and if the primary MX times out or cannot respond, mail is routed to the secondary and tertiary in an order and volume based upon that priority.

2. Check that your mail server is listening on the mail port 25 using netstat. Check the ADDRESS it is listening on. If it is then it is not listening for external mail, but local mail only. Change its configuration to make it listen on all ports.

PS: if your users pick up mail from the primary, you may have to configure it to accept mail from this secondary, and the secondary to forward mail it cannot deliver to the primary. Be careful not to define a loop.

Papi_Linux_Server 08-29-2011 01:07 AM


sorry for taking so long to respond. how do i configure MX Records? I installed bind9 and tried following the steps provided in the linux guide but still no luck.


wpeckham 08-30-2011 09:24 AM

Looking over your traffic...
Re-examining your traffic, I have a few questions.
1. Is this one also supposed to receive mail for the company along side the pre-existing one, or only receive mail from your internal network?
2. Where is the MX record defined for your pre-existing mail server? (In a DNS you own, or one at your ISP?)
3. Who manages your DNS records, you or your ISP?
4. WHY does your company want a second mail server? (failover, handle greater volume, etc.)

Papi_Linux_Server 09-01-2011 07:30 AM

To answer your first question,
this mail server is supposed to work along side the pre-existing one but when people send emails to this domain its first supposed to look in the pre-existing server when it does not find the mailbox for the recipient its supposed to look in my server.

i think the mx records for the pre-existing server are defined at the ISP in Belgium and the DNS is managed by the ISP.

I dont know why the company wants a new server but i think it has something to do with cutting costs.

wpeckham 09-02-2011 09:33 AM

second mail server
I am not sure how a second server will save costs, but understand that they will run in parallel.

Since the other server is forwarding all mail for your domain that IT cannot deliver to this Second server, you cannot set this one to forward undeliverable mail to the first mail server. Doing so would create an endless loop for mail that neither could deliver. That means that ALL mail needs to go to the first mail server, and what it rolls over goes to the second mail server, where it will be either delivered or dropped. No additional MX record is required for this, and your secondary does not need to be able to receive mail from anything but the first mail server. You may need an MX record for the new mail server so that sites receiving mail FROM it will be able to do an MX lookup to verify it. You would request the MX entry be entered into the DNS by the ISP that manages DNS for your domain.

I have run a corporate site with two mail servers doing content and RBL filtering (and load sharing) for all inbound mail, and forwarding all valid mail to an internal mail server. (The balanced pair ran Tru64 and sendmail, the internal was MS Exchange. We cut spam by 90% and saved around $150k in man hours monthly.) I have never configured a two-node mail pair as you are considering, and I do not really understand the value. Perhaps someone will chime in who better understands why this is a good idea and how it will save money.

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