Google Indexed a version of my site w/ MX record subdomain

[SS.Digital]

We're doing a site audit and found "internal" links to a page in search console that appear to be from a subdomain of our site based on our MX record.  We use Google Mail internally.  The links ultimately redirect to our correct preferred subdomain "www", but I am concerned as to why this is happening and if it can have any negative SEO implications.

Example of one of the links:

Links
aspmx3.googlemail.com.sullivansolarpower.com/about/solar-power-blog/daniel-sullivan/renewable-energy-and-electric-cars-are-not-political-footballs

I did a site operator search, site:aspmx3.googlemail.com.sullivansolarpower.com on google and it returns several results.

[willcritchlow]

You appear to have the MX sub-domain also set up as an A record.

If you have a mac / linux you can run the command: host aspmx3.googlemail.com.sullivansolarpower.com

You get the result aspmx3.googlemail.com.sullivansolarpower.com has address 72.10.48.198

Where you should get the result "not found".

I think you want to delete the A record (though check the documentation of your email provider first). You should only need them set up as MX records and shouldn't need the A record.

You've done the right thing by setting up the redirect - which should mean that the pages drop out of the index and those links disappear. (Note that there is also an https error on the aspmx3 sub-domain - but given that you don't actually want it, I don't suppose that matters that much).

Hope that helps.

[SS.Digital]

I did not explain the problem thoroughly.  The problem is, the link does not actually exist anywhere.  To make a very long story short.  There was an issue with server configuration for a period of a couple months.  During that time, an unknown number of non-existent subdomains got indexed.   Basically, if anyone had a typo in the subdomain when accessing our site, it would get cached and if Google crawled our site before we cleared the cache, the typo subdomain would get indexed.  Over a period of a couple months, many bad subdomains were accidentally created and indexed by Google.  We do not have any way of finding a comprehensive list of all of them.  This problem has been resolved so we are not getting new bad subdomains created and indexed, but the damage has been done.

The way our site is setup currently, any attempt to reach our site with any subdomain other than "www" gets redirected to "www.sullivan..."  Also, any nonsecure protocol gets resolved to https://

The actual problem, simply put is this:  Google has an index which includes some number of unknown, non existent subdomains.  We need to get rid of them and cannot figure out how.

Example:  Copy and paste the following into google and search it:

site:aspmx3.googlemail.com.sullivansolarpower.com

Google will return two results.  If you click on either, it resolves to the "https://www. version of the page.

I know it is confusing, but does that make sense? I have searched everywhere, but the reason this happened was because of a perfect storm of server configuration issues and I cannot find anyone else who has had the same problem.

If it were one or two bad subdomains, we would just put them into search console and then get "remove URL" for the entire subdomain.  But it is not 1 or 2.  It is at least 10 that I know of and could be hundreds for all I know.

Does anyone have any ideas?  Any and all would be welcome.

Thank you.

[Tenlo]

You should find the locations of those links and correct them to point to the proper URL. I find that Screaming Frog's crawl is the easiest for this, you can find every link and see where they are located.