I’ve been using Google Apps, aka Google Workspace aka Google Suite (or just G Suite) for a while now and it’s annoyed me that I was getting “marked down” on e-mail security testers such as Internet.nl and the UK Government’s National Cyber Security Centre (NCSC) Check Your Email Security Service because Gmail for Business (G Suite) didn’t support DNSSEC (Domain Name System Security Extensions) signed MX hosts.
However, I’ve managed to find Google’s DNS Sec settings which – combined with other setups on my main domains – mean I get 4 green ticks from the NCSC, 97% from Internet.nl (I’m let down by Google’s support of old TLS and Ciphers settings and no DANE TLSA records) and all green (apart from DANE) on Hardenize : so nice strong secure email!
Read more: DNSSec signed Google Apps/G Suite EmailGoogle normally suggest you use the following MX (Mail Exchanger) records in your DNS settings if you use G Suite:
| Priority | Mail Server (MX Entry) |
|---|---|
| 1 | ASPMX.L.GOOGLE.COM |
| 5 | ALT1.ASPMX.L.GOOGLE.COM |
| 5 | ALT2.ASPMX.L.GOOGLE.COM |
| 10 | ALT3.ASPMX.L.GOOGLE.COM |
| 10 | ALT4.ASPMX.L.GOOGLE.COM |
(The records can actually be in any order and the priority can be anything – but Google do recommend that aspmx.l.google.com is set as the “highest priority” which is actually 1)
However, after a bit of searching (using DuckDuckGo and not Google 😉 ), led me to a blog post by Nis Bornoe and Kura the following G Suite DNSSEC signed MX records:
| Google’s DNSSEC Signed Mail Servers (MX Entry) |
|---|
| mx1.smtp.goog |
| mx2.smtp.goog |
| mx3.smtp.goog |
| mx4.smtp.goog |
These domains are hosted on Google owned Charleston Road Registry (CRR)’s .goog top level domain (not to be confused with their .google and .gle brand top-level domains: or the 98 other ones they applied for) and .goog domains can “only be registered to Google Inc and its affiliates” so you’ve got some confidence they are legitimate.
However, whilst myself and Nis and Kura do not seem to have had any problems using these IPv4 and IPv6 supported DNSSEC signed nameservers (and according to DNSlytics and WhoisXMLAPI there are over 930 domains currently using them), they are not officially supported or documented (from what we can find) and have been running since at least 2019 – so they should be reasonably safe to use.
The only “catch” may may be that, for some reason, they do NOT have a reverse DNS (Pointer aka PTR) record setup – which is actually only a problem if those mail servers are use for sending OUT email (not just receiving it) – however, many only testers do assume that your inbound and outbound mail servers are the same. I can confirm, via a test email, that outbound mail goes out via servers such as mail-wr1-f52.google.com which are correctly configured.