MX Guarddog IP Address List

Frequently Asked

MX Guarddog publishes our IP Addresses for email administrators who wish to perform server hardening for prevention of direct delivery, this information is published for advanced users only.

If you are controlling access to your email server by IP Address, you will need to allow our delivery servers to connect from the following addresses.

Allow access from all addresses to guarantee your email can be delivered. We try and make as few changes to this list as possible... and will inform all impacted customers via email of any upcoming changes.

Active MX Guarddog IP Addresses

64.38.239.80/29	Phoenix AZ, USA	Added Aug. 2014 All domains must accept mail from this address range.
207.81.189.178/32	British Columbia, Canada	Added Nov. 2018 Domains added November 1, 2018 or later must accept mail from this address range.
66.228.130.216/29	Dallas TX, USA	Added Nov. 2021 Domains added November 1, 2021 or later must accept mail from this address range.
38.246.57.224/29	Phoenix AZ, USA	Added Jan. 2026 Domains added January 1, 2026 or later must accept mail from this address range.
Here are a couple examples: >>> If you added your domain to MX Guarddog on March 5, 2026 you would need to accept mail from all IP addresses listed above. >>> If you added your domain to MX Guarddog on February 14, 2019 you only need to accept mail from the 1st two IP ranges listed.

Resolution By Name

If you have one of those fancy firewalls that can apply rules by using a host name, we got you covered. We publish a list of our active IP addresses under the name servers.ik2.com.

Retired IP Addresses

Retired addresses are no longer being used, if you previously allowed access to any of these addresses you can now safely remove them.

208.77.151.112/29 - retired November 2021
122.103.250.12 - retired May 2021
85.195.83.79 - retired January 2017
66.85.178.50 - retired October 2014
108.166.117.93 - retired October 2014
64.15.147.141 - retired July 2014
216.58.39.211 - retired March 2014
174.129.28.137 - retired March 2014

General Questions If your email is protected by MX Guarddog, but you're not the postmaster you will find the most relevant questions answered on the general page.
Pre-sales QuestionsIf you are still considering MX Guarddog to protect your organization's email you will find your questions answered on the pre-sales page.
Technical QuestionsYou are the the postmaster for your organization, have a question? You will find lots of answers about how things work around here on the tech pages. Things can get quite techie in here, so be sure to wear your pocket protector.
Billing QuestionsAre you the bean counter? If you have a question regarding invoices, payments, earning tokens or something else accounting related check for answers on the billing page.