Your mail server Internet Protocol could get added to the blacklist if incorrect setting up of DNS is done. If on the spam blacklist you are listed, then all the inbound mail to come, gets blocked when secure mail server is given to the email servers, these days.
If DNS records have to be reversed to the business email server then the MX will have to be configured correctly and this very same principle can be followed for a messaging server of every kind. For the mail servers, to the private address internally, a static IP address has to be set up externally which is the first thing that needs to be assigned for email hosting.
Check the Outgoing NAT Rule
These rules will need to be applied on the firewall so that SMTP or Port 5 can be port forwarded besides which even an external IP address that is NAT is also port forwarded to the server’s internal address. One thing that is generally forgotten by many of the administrators is doing or checking if the NAT rule that is outgoing is set to use the very same IP address created externally for the inbound rule to the webmail server.
When this setting is not done then the reverse DNS does not match and in turn blacklisting of your email server is done on the list. When setting up of the firewall rules is done correctly the listed IP address on the page should be very similar to the IP address that has been mapped to the email server’s private IP address that is set up internally.
Need For an Administrative Contact for Making Changes
What do you have to do if for your business email server MX records have to be created? For your DNS provider for the domain there will need an administrative contact for making the changes. Via a control panel on the internet through a provider for DNS this can be done. If this is not done then the changes will have to be made via email or the phone.
A record for pointing the IP address that is mapped externally is first created on the webmail server’s firewall, called the mail. To point the A record created for the email service, an MX record can now be created. Now ‘add MX record’ will have to be selected in the DNS control server and as A record now set the FQDN but make sure that the lowest property is preferred.
Check Whether the MX and DNS Records Have Been Applied
The next thing to do is checking whether the MX and DNS records have been applied and for this you will have to use NS look up. Next the reverse DNS will have to be configured and then verified. An SMTP Banner will be shown each time a connection is established by the external email server with your server for email hosting.
It is important for the banner to be resolvable on the internet and hence to have it as an A record mail host is the best practice. Accordingly the SMTP Banner Exchange can be configured. Once this is done you will need to check if on the spam list or on in an open relay, the secure mail server is listed or not.