Basically, it’s another “WTF, Google?” email. I mean if you received it, that’s good, because it means that your site is verified with Google Search Console / Webmaster Tools, perhaps the best SEO Tool available.
And if you didn’t receive it, it doesn’t mean your SEO / Web Design company doesn’t know what they’re doing, but it could mean that, and you definitely need to check with them to make sure they have your site verified with Google and that they’re receiving this message. We’ve received one for all of our clients’ sites, and here’s what it means…
From all of this text from Google, the key portion that you need to pay attention to is bolded and italicized below…aka, you don’t need to do anything. Your site is in great shape.
This means that you may see more traffic in your logs from Googlebot Smartphone. You may also see that snippets in Google Search results are now generated from the mobile version of your content.
Background: Mobile-first indexing means that Googlebot will now use the mobile version of your site for indexing and ranking, to better help our (primarily mobile) users find what they’re looking for. Google’s crawling, indexing, and ranking systems have historically used the desktop version of your site’s content, which can cause issues for mobile searchers when the desktop version differs from the mobile version. Our analysis indicates that the mobile and desktop versions of your site are comparable.