98 votes
Accepted

Why can't MX records point to an IP address?

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 ...
49 votes
Accepted

DNS MX/SPF/DMARC records without actuall emails on domain

The point would largely boil down to being a good citizen and reducing abuse, like making your domain less useful for spammers to impersonate and to make it immediately clear to others that mail is ...
44 votes
Accepted

Is it bad practice to declare MX from differing networks?

They are mostly wrong. It is not a bad practice to have more than one MX, and it's equally not a bad practice to have one or more of them with a hostname in another domain. In fact, it used to be ...
  • 27.5k
24 votes

Is it bad practice to declare MX from differing networks?

No, this is BS. Having this option is one of the main reasons why you can specify multiple MXs with different priorities in the first place. There must be another problem.
  • 97.9k
22 votes

Why can't MX records point to an IP address?

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 ...
22 votes
Accepted

Multiple MX Records handling

MX records are used according to priority value in the records. The record with the lowest priority is used first, then the higher ones until one responds. If there are multiple records with the same ...
  • 3,416
19 votes
Accepted

Replacing an MX record with a CNAME that doesn't match the hostname

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 §10.3: 10.3. MX and NS ...
  • 32.1k
16 votes
Accepted

MX record point to itself, possible?

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 ...
14 votes
Accepted

MX priority server behaviour

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 ...
  • 3,713
14 votes
Accepted

Issue Creating Two MX Records with Different Priority Using Google Domains

You should click the Edit button in the MX record that Google considers valid, click '+' and add the second MX record
13 votes
Accepted

What does MX in SPF mean?

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 ...
  • 7,983
12 votes
Accepted

MX records, better setup for load balancing and failover

The RFC's that specify how a MTA should handle MX records are RFC974, RFC1123 section 5.3.4, RFC2821 section 5 and RFC5321 section 5. RFC974 status is now HISTORIC. According to it, MTA's are ...
12 votes
Accepted

Why would email deliver normally when MX Lookup test returns "DNS Record not found"?

Your domain does not have an MX record. But an MTA is listening on the A record's IP, and that is the fallback of SMTP in case there is no MX record.
  • 5,235
11 votes
Accepted

record DKIM on IONOS makes sense?

it is IONOS who signs those emails, right? It would be, if they signed them. But they don't. (But they should.) Here are some excerpts of a conversation I had less than 10 minutes ago with their ...
11 votes
Accepted

Why isn't the MX record propagating after pointing a domain to Yahoo Mail Server?

I took a look, unfortunately I couldn't find an MX record, the SOA record shows me that something was last changed to the dns records on March 23. When did you make your changes? ;kmtc.com.sa. ...
  • 126
11 votes

Why isn't the MX record propagating after pointing a domain to Yahoo Mail Server?

DNS doesn't propagate; the responses from authoritative servers are cached by the recursive servers. Currently your authoritative servers are responding with an empty set of MX records, so they are ...
  • 44.6k
11 votes
Accepted

MX record with only one dot, possible?

An MX record consisting of only a single dot . is a Null MX as defined in RFC 7505. It means that the domain doesn't accept any email.
  • 8,304
10 votes
Accepted

Do I need an SSL certificate for a .DEV TLD on an MX record?

No, or not necessarily. .dev like all new Google TLDs (including .new in one month) has been added to the HSTS Preloading list. It means that all names under this TLD will force browsers (because ...
10 votes

Multiple MX Records handling

MX records cannot solve this, multiple records (with possibly different priorities) can be used for redundancy, but the service is expected to be the same (accept the same addresses). What you can do ...
9 votes

Are SPF needed for domains that do not send mails and do not have MX record?

If you don't intend to send mail from this domain, why let anyone else to use it as they wish? But things have changed since this question was asked eight years ago. SPF can only protect your domain ...
  • 44.6k
9 votes
Accepted

Is an MX-record required on a domain to send emails only?

No and yes. By standard, your sender domain is not required to have an MX record. RFC 5321 makes an MX record optional. However, an MX record is somewhat of a standard today. Due to spamming practices,...
  • 9,162
7 votes

DNS using CNAMEs breaks MX records?

RFC2181 section 10.3 says you can't point your MX record to a CNAME: The domain name used as the value ... of a MX resource record must not be an alias.
7 votes
Accepted

Multiple MX records pointing to multiple servers for a single domain

Yes, you understand it correctly. Sending E-Mail servers use MX records in order of preference defined within the MX records. The record with smallest precedence is used first, then the second ...
7 votes

MX or A record issues

RFC 5321 section 2.3.5 requires that domain names used in email be resolvable to addresses. From the relevant parts: Only resolvable, fully-qualified domain names (FQDNs) are permitted when domain ...
7 votes
Accepted

Seperate web/mail server, mailserver won't receive emails

Your domain hasn't actually got an MX record. $ host -t mx samholguin.co.uk samholguin.co.uk has no MX record Without an MX record, mailers will fall back to trying to deliver to an address for the ...
7 votes
Accepted

How to include multiple spf domains with different mechanisms in a single spf TXT Record

You can combine them all like this. v=spf1 a mx ptr ip4:x.x.x.x ip4:y.y.y.y include:mktomail.com include:icpbounce.com include:spf.mandrillapp.com -all I recommend changing the ~all to -all - ...
  • 920
7 votes
Accepted

Recover Live.com Custom Domain MX Records

This took many, many, many hours of Google-Fu (about 18 hours, give or take). You have to first log in to your Outlook.com account that you're missing your records on. This must be done on a browser ...
7 votes
Accepted

Postfix: Name service error for name=domain.com type=MX: Host not found, try again

Well, this is embarrassing. As I predicted my problem was caused by the most obvious and trivial reason: lack of read access to /etc/resolv.conf for the postfix user o_0 As you probably know the ...
7 votes
Accepted

Why do I see so many domains from businesses without MX records?

These sites are misconfigured. Roughly 15 years ago such configuration would be a sure pointer to an IT department running on windows without a clue about the internet. This hasn't changed much. Many ...
  • 1,929
7 votes

Base64 encoded MX records in TXT records

My guess is this: NOTE 1:In case you do not want to interrupt the functionality of current email services before the creation of mailboxes with us we have an alternative verification method that ...
  • 17.8k

Only top scored, non community-wiki answers of a minimum length are eligible