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68

The whole idea behind the MX record is to specify a host or hosts which can accept mail for a domain. As specified in RFC 1035, the MX record contains a domain name. It must therefore point to a host which itself can be resolved in the DNS. An IP address could not be used as it would be interpreted as an unqualified domain name, which cannot be resolved. ...


30

This is a common error. You cannot use a CNAME RR for your root domain (e.g. company.com) and define additional resource records for the same zone. See Why can't I create a CNAME record for the root record? and RFC1034 section 3.6.2 for details: If a CNAME RR is present at a node, no other data should be present; this ensures that the data for a ...


28

http://whoisrequest.org/history/ This one is really cool . No registration needed .


23

According to RFC 1123, the MX record cannot point to a CNAME. If I were in your situation, I would setup mail.ourdomain.com as an A record pointing to the new suppliers IP address and then quickly work on changing all MX records over to the correct data. Then address why changing MX records is so difficult in your organization. That being said, most mail ...


22

As long as the system pointed at by the MX record has an A record itself, then yes. For example: example.com can have a MX record pointing at mail.otherdomain.com. As long as the name mail.otherdomain.com itself is resolvable to an IP address, this is a valid configuration for example.com. Strictly speaking, mail.otherdomain.com should be an A record with ...


19

If you set up a name for this server, like mail.example.com. IN A 1.1.1.1 then you set up a MX server like example.com. IN MX 10 mail.example.com.


19

Yes, it would be possible, but you will lose some important advantages if you choose to do so: If you point all services to the same DNS name, you can't put them onto separate servers any more without reconfiguring any client that refers to them. As an example: With different names, when the load on the server grows too much, you can simply offload the ...


17

Hotmail fails to use proper DNS rules. Hotmail will always try to deliver to the domain's A-record first and will ignore MX-records. If the domain A-record accepts a connection (eg. it runs a mailserver) it will try to deliver the email, which in most cases will not be an issue if the webserver and mail server are the same box. However, if an domain uses a ...


17

It would definitely create a problem if you were to point your MX records at CNAME records since it is against the standards. The clearest explanation is provided by RFC2181 ยง10.3: 10.3. MX and NS records The domain name used as the value of a NS resource record, or part of the value of a MX resource record must not be an alias. Not only is ...


16

it used to be the case that having a backup MX was a Good Thing. the internet was unreliable, email was unreliable, smtp was not so common, bang-path addressing and other forms of manually-specified mail routing was common, and uucp was the mail protocol of choice. That was a long, long time ago. It's not true today. sending MTAs will queue up ...


16

Just use a telnet session to test email delivery. As an example, # telnet host.domain 25 Trying host.domain... Connected to host.domain. Escape character is '^]'. 220 ESMTP HELO example.com 250 MAIL FROM:<user@example.com> 250 ok RCPT TO:<user2@example.com> 250 ok DATA To: user2@example.com From: user@example.com Subject: a test message Test ...


15

MX records were invented for precisely this application: allowing mail for a specific host to be handled by another host. The first thing to point out is that MX records do not contain IP addresses, they container a pointer to a hostname. So for your example you would have something like: abc.tv. A a.a.a.a MX 5 mail.abc.tv. ...


15

DNS as a protocol has some different types of values, these are not interchangable. It's important to note that DNS is a binary protocol with strict mappings between the type of record and the type of data that such a record holds. For example: An A record holds an IPv4 address (4 bytes of data, fixed length). An AAAArecord holds an IPv6 address (16 bytes ...


14

Do yourself a favor and set them up with a gateway anti-spam service such as Postini. For a few dollars per mailbox per month, there's absolutely no reason not to and you'll not only eliminate 99% of your spam, you'll also enjoy having access to their spool service (handy for scheduled or unscheduled downtime), not to mention the bandwidth savings by ...


14

An MX RR pointing to itself is perfectly valid and will cause no problems. It may be considered redundant, though, because of the general rule that if a domain name has no MX RR but an A RR, the latter shall be used for mail delivery. In other words, an MX RR pointing to itself is implicitly assumed when no explicit MX RR is present. Note that your example ...


14

Under normal circumstances the server will connect to the first one that is available, but there are many reasons the first one may be unavailable to one person but not the next. Some of these reasons include things you have no control over. However the general rule is try from lowest to highest until there is a response and then use that server. Where ...


13

After a lot of work and research here, I have found an acceptable solution. First, it is important that we all follow the RFCs. I patched my DNS server to violate the RFC, and I discovered that several other major DNS servers would not respect the change. The appropriate move is to put the MX on the host that the CNAME points to. So, if ...


13

Unfortunately, what you're running into is a limitation of the DNS specification. Having an MX record for the same hostname as is defined as a CNAME record will fail in most DNS server implementations. Some older DNS servers will allow this, but they have been mostly phased out in favor of newer, more secure implementations. Instead of using CNAME ...


13

http://dnshistory.org/ Seems to have a patchy history, all for free.


12

I've tried this, and I can strongly recommend that you DON'T DO IT! It seemed like a good idea at the time, but after mail from various senders starting disappearing, I realized that it was a mistake. What I didn't realize was that there are lots of terribly written SMTP servers out there, that don't follow the spec and are fairly bad at handling errors, and ...


12

You will need to correct the MX records in your DNS which is probably hosted on your server at Rackspace. You can locate the MX records you need in the Email Control Center. Here is a guide to do so: http://support.godaddy.com/help/article/5444


11

Put periods on the ends of the MX records. (Forceds them to be FQDN instead of relative).


11

To make things nice and clear, as some of the GoDaddy help articles are dead wrong: You just need to paste the two records from the server settings into your Route 53 control panel as a new record. The possible deception here is the the GD email panel will tell you you're wrong, but not what is right so you can make it right. Further, their help ...


11

Yes, an MX record is there only for incoming mail.


10

An MX record must be a name, not an IP. That means the host pointed to by an MX record for your domain must itself be directly resolvable to an A record. However there is no requirement for that A to be part of your domain. For example you can have Google Apps handle the MX records for your domain, while you manage the A records for the domain and www.


10

It's an RFC violation to use a CNAME as an MX record. From RFC2181 section 10.3: The domain name used as [...] part of the value of a MX resource record must not be an alias. [...] It can also have other RRs, but never a CNAME RR. In practice it will often work, but some MTAs are aware that you shouldn't do it, so assume they can ignore you or ...


10

Definitely a NO, not with a 127.0.0.0 IP.The entire 127.0.0.0 range on IPv4 works as loopback addresses, thus when any machine connects to IPs in that range it will try to connect to itself. Your MX record IP address should be accessible from the outside world and what that result is telling any server doing a MX query, to try to connect to itself. If my ...


10

The first MX means that the IP addresses in the MX record(s) for the domain you're actually attaching the SPF record to should be accepted as valid. The second one means that IP addresses in the MX record(s) for the domain mail.mydomain.com should be accepted as valid. If this SPF record is for the domain mail.mydomain.com, then the second one is redundant. ...


9

You can't do this by indicating multiple the MX records for the same (sub)domain. The mail will be delivered to the server(s) defined by your MX record regardin only the (sub)domain, without any look at the user@... Mail routing is done on the (sub)domain part only. Possible solutions : You can use subdomains, to re-route easily : me@sub.domain.com . The ...


9

A word of warning: An MX record provides information about where email should be delivered. It does not necessarily provide any information about where email originates. It is entirely possible -- even likely -- that mail will be coming from a system that is not listed as an MX for the given domain. SPF records, on the other hand, allow you to verify ...



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