You must have an MX record to send or receive e-mail from your domain's email addresses. You can check if your MX records are set correctly with this tool.
DNS (Domain Name System) is a service that translates domain names into IP addresses. Users can easily remember domain names, but he computers understand IP addresses that’s why we need DNS. For example, without this service, you have to type '18.104.22.168' in your browser instead of www.facebook.com to access Facebook. IP - Domain mappings are kept on DNS servers. You can query those matches on securityforeveryone.com
There is two type of IP addresses IPv4, and IPv6. IPv4 address looks like these:
22.214.171.124 127.0.0.1 255.255.255.255
IPv6 addressed looks like these (all of them are the same IP):
::ffff:808:808 0:0:0:0:0:ffff:0808:0808 0000:0000:0000:0000:0000:ffff:0808:0808
A MX Records (stands for Email Exchanger Record) is hold a domain name which is responsible for accepting emails.
Without MX record, e-mail services couldn't know where to deliver emails. Let's give a real-life example and send a mail to email address ending with @securityforeveryone.com. To to that we have to;
DNS MX record must have a valid hostname address (such as mail.securityforeveryone.com) and a prioritization value. Lowest value means that it will be chosen first. If it is unreachable, other options are tried.
Easiest way to do that is using our free and online DNS MX Record lookup tool. Write your domain in the search field on top of the page.
Or if you are using a Linux or an OS X operating system, open terminal and type dig -t mx yourdomain.com. If your domain has a valid MX record, it would look like that:
dig -t mx securityforeveryone.com ;; ANSWER SECTION: securityforeveryone.com. 299 IN MX 10 mx.yandex.net.
10 is a value for prioritization. And mx.yandex.net is a hostname to send and receive email.
If you are using Windows open powershell and type Resolve-DnsName -Name yourdomain.com -Type A
If your MX records don't look the way you want, you need to configure your DNS settings correctly.