?
Solved

Secondary MX records

Posted on 2009-02-20
6
Medium Priority
?
498 Views
Last Modified: 2012-05-06
Hello,

I am trying to get a better understanding of how MX records work. I have only ever setup exchange servers with one MX record. If I added a secondary MX record will mail get sent to that additional server too? What I am trying to get is something that will still recieve mail if the primary MX is not reachable....and once it comes back up again I need something where secondary MX will then re-send all the mail the primary server missed. Is this possible?
0
Comment
Question by:Dan560
6 Comments
 
LVL 18

Assisted Solution

by:flyingsky
flyingsky earned 600 total points
ID: 23692512
You can set up a secondary MX record, just give it a higher reference number than your primary one. But I don't believe you can setup it to automatic re-send emails once the primary one is up.
have a look at here, especially the "Multiple Mail server" part
http://bobcares.com/index.php/blog/?p=29
0
 
LVL 6

Assisted Solution

by:Syedm2
Syedm2 earned 600 total points
ID: 23692656
Normally, a secondary MX record is configured and pointed to the ISP.
So,if the primary MX pointing to ur mail server is down,it would failover to the secondary MX record and ur isp will keep ur mails till ur server is up.
then,once it is up they will send all emails to u.
So,it works as fault tolerance so u dont loose any emails.
MX priority is what determines the primary and secondary MX.
Have a look at this:
http://www.dnsmadeeasy.com/s0306/prod/mailbk.html
http://linuxgazette.net/issue36/tag/80.html
0
 
LVL 65

Accepted Solution

by:
Mestha earned 800 total points
ID: 23693132
I have to disagree with the above post about "normally" MX records being pointing to an ISP. I wouldn't say that was normal at all.

In theory, MX records should work where all email is delivered to the address with the lowest cost. The server with the highest cost only gets email when the lowest cost is not available.

In practise, that doesn't happen. I find that email will go to all servers in the MX records. I am running a long term test involving my own MX records and that of one of my clients. We both have multiple Internet connections and multiple SMTP gateways. I am finding that the split is roughly 60/40 in favour of the lower cost MX record. IE, 40% of email comes in via the higher cost server.
I am also finding that about 80% of spam traffic is coming in via the higher cost record because spammers specifically target them. The theory with that idea is that the higher cost has a lower level of spam protection because the email administrator doesn't think it will get the same traffic.

I am not a fan of backup MX services because of the limitations in their service.
The DNS Made easy service above gives a classic reason why - they cannot defend against a directory harvest attack.

What I prefer to do is use a dynamic DNS account to give me control over where the email goes constantly.
http://www.sembee.co.uk/archive/2007/02/02/38.aspx

-M
0
Transaction-level recovery for Oracle database

Veeam Explore for Oracle delivers low RTOs and RPOs with agentless transaction log backup and transaction-level recovery of Oracle databases. You can restore the database to a precise point in time, even to a specific transaction.

 
LVL 6

Expert Comment

by:Syedm2
ID: 23693284
I disagree to ur post as well
0
 
LVL 2

Author Comment

by:Dan560
ID: 23704145
Thanks, so there is no way the secondary MX server can resend the mail to primary MX when it comes backup?
0
 
LVL 65

Expert Comment

by:Mestha
ID: 23705133
You have to look at how the email gets passed from one host to the next.
Where I have put in place relay servers they have been exactly that - relay servers. All they do is queue the email and wait for the original server to come online. You cannot get access to the messages.
To get access to the messages you either need a queue viewer (which will only show you the raw messages) or you have to deliver the messages to a mailbox. Once the messages are in the mailbox it isn't possible to forward them on to the Exchange server without doing each one individually.

Most backup MX type systems are simply queueing servers, with a queue viewer functionality bolted on top. Most ISPs will not give you the viewing option, so you would have to wait for the email to come down.

-M
0

Featured Post

Fill in the form and get your FREE NFR key NOW!

Veeam is happy to provide a FREE NFR server license to certified engineers, trainers, and bloggers.  It allows for the non‑production use of Veeam Agent for Microsoft Windows. This license is valid for five workstations and two servers.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Steps to fix error: “Couldn’t mount the database that you specified. Specified database: HU-DB; Error code: An Active Manager operation fail”
There can be many situations demanding the conversion of Outlook OST files to PST format and as such, there is no shortage of automated tools to perform this conversion. However, what makes Stellar OST to PST converter stand above the rest? Let us e…
In this video we show how to create an email address policy in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.:  First we need to log into the Exchange Admin Center. Navigate to the Mail Flow…
To show how to create a transport rule in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Mail Flow >> Rules tab.:  To cr…
Suggested Courses

839 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question