How to serve first party cookies with Mautic - one instance, several domains

Yes, you are safe with your setup.

Until the second level domain is the same, there are no issues.

Which is the error? If you don’t post it we cannot know which the problem could be.

Are you sure dns are correctly propagated? Did you created a correct ssl certificate for Can you access Mautic going to

Mautic is installed at

The wordpress site in question is NOTE: the tracking script is only located on the homepage for testing purposes, it’s not in the header at the moment.

The CNAME is set up to point to

I can access my Mautic install at, so the DNS seems to be fine.

I verified that and are both SANs in the certificate.

From the Google Chrome console

A cookie associated with a cross-site resource at was set without the SameSiteattribute. A future release of Chrome will only deliver cookies with cross-site requests if they are set withSameSite=NoneandSecure. You can review cookies in developer tools under Application>Storage>Cookies and see more details at and

If I edit the URL Field under Settings > URL to ", then the issue goes away (but of course it would break it on the other site).

Which version of Mautic are you running?

Current Mautic version is 2.16.3

The only thing I can come up with is somewhere (the actual domain of the mautic install) should be rewritten to (the cname).

Does this KB exist yet? Would love to read it!

Has this feature been recommended for integration in Mautic core? If not, is there a way to request features? We are migrating from SharpSpring and this is standard feature now over there as well as on all the MAPS we have used – Marketo and Hubspot. Considering the wide use of microsites and product specific domains for modern content marketing, this seems like it should be standard part of Mautic too.

Check this post: