To solve this problem u sing CIDR notation, Google’s 4,096 IP addresses are represented as: 64.18.0.0/20. Listing each IP address individually in the SPF record does not work because the record exceeds the 255 character TXT record limit. Use IP Address Guide to convert an IP address range to CIDR or a CIDR range to IP addresses.įor example, Google uses 4,096 IP addresses that range from 64.18.0.0 - 64.18.15.255.Using CIDR notation for a single IP address works, it is just unnecessary. Multiple, sequential IP addresses using CIDR notationĬIDR notation is a compact representation of a sequential range of IP addresses. It is uncommon to send email from both an IPv4 and IPv6 address, however, you can add each type of address in the same SPF record if required. If the number of IP addresses in your SPF record exceeds 255 characters, investigate different options to shorten your SPF record. You can add as many IP addresses as needed to your SPF record up to the 255 character TXT record limit. A single IP address Multiple, non-sequential IP addresses Multiple, sequential IP addresses using CIDR notation A single IP address. Multiple, sequential IP addresses using CIDR notation.There are three ways to include IP addresses in your SPF record. ip6:2001:4860:4000:4uh5:b2fw:0000:8e5d:6432Īn incorrect IP mechanism for your IP address in your SPF record results in a failed authentication check.If you have an IPv6 address, the IP is included in your SPF record with an ip6 mechanism. If you have an IPv4 address, the IP is included in your SPF record with an ip4 mechanism. IPv6 addresses are not widely used at this time.

Most organizations and ESPs use IPv4 addresses. There are two IP address versions you may need to include in your SPF record: IPv4 and IPv6. Including IP addresses in your SPF record Sending email from an IP or domain not included in your SPF record results in a failed authentication verification. An SPF record is your way of telling mailbox providers which IP addresses or domains are authorized to send mail on your behalf, so it is very important that it is accurate and up to date.

Forms to go include ip address