Our IP ranges change regularly and we don’t recommend whitelisting based on IP address. In order to obtain all necessary information to whitelist CheckMarket we suggest you send a preview invitation to your IT department. They can get all necessary information from the mail headers. If they do request specific IP ranges, please send them the instructions in this article.

Currently our IP ranges are:

• 199.255.192.0/22
• 199.127.232.0/22
• 54.240.0.0/18
• 69.169.224.0/20
• 23.249.208.0/20
• 23.251.224.0/19
• 76.223.176.0/20

We reserve the right to change these IP ranges at any time without prior notice.

CheckMarket maintains a number of IP addresses from which your email can be sent, and you can figure out those addresses by querying CheckMarket’s SPF record. If you keep following up the SPF trail, you will finally get the IP ranges.

Query in a Linux Terminal window

Here’s how to do the query in a Linux terminal window (including a filter to include only the SPF record):

$ dig TXT chkmkt.com +short| grep 'v=spf1'

At this time, the DNS response returned for that query:

"v=spf1 ip4:199.255.192.0/22 ip4:199.127.232.0/22 ip4:54.240.0.0/18 ip4:69.169.224.0/20 ip4:23.249.208.0/20 ip4:23.251.224.0/19 ip4:76.223.176.0/20 -all"

Query in the Windows command prompt

Here’s the equivalent query (and result) using the Windows command prompt:

C:\>nslookup -type=TXT chkmkt.com | find "v=spf1"

"v=spf1 ip4:199.255.192.0/22 ip4:199.127.232.0/22 ip4:54.240.0.0/18 ip4:69.169.224.0/20 ip4:23.249.208.0/20 ip4:23.251.224.0/19 ip4:76.223.176.0/20 -all"

You can also use a number of online tools like DNSstuff to perform a similar DNS query for you, but it’s up to you to determine how reliable and trustworthy they are.

Any email sent through CheckMarket will be sent through one of the IP addresses listed in the record.

In this example, which is valid at the time of the writing of this article, we can see that CheckMarket is using seven blocks of IPV4 (32-bit) addresses.

The blocks are defined using CIDR notation: each block is specified as an IP address followed by the ‘/’ sign and then the number of bits in the prefix. The 199.255.192.0/22 block, for instance, designates all IP addresses that have the first 22 bits equal to the first 22 bits of 199.255.192.0, with the remaining bits taking all possible value combinations. Therefore, that block designates all addresses in the interval 199.255.192.0 – 199.255.195.255.

Keep in mind that those IP addresses are subject to change. If CheckMarket adds or removes any outgoing IP address, we will update the SPF record, so you need to check back from time to time, if you want to make sure you have the latest list of IP address ranges.

Another thing to note is that there is no guarantee with regard to which particular CheckMarket  IP address of the list of IP addresses, your email will be sent through. If you need to perform a whitelisting process for the emails you’re sending through CheckMarket you will have to whitelist all CheckMarket IP address blocks.

Also note that we send all emails using TLS and we sign all emails using 2048 bit DKIM.

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