Just to let you know that I have verified some mirrors last week and sent several mails to the contact info we had for those mirrors (unreachable/far behind).
I've received feedback from some people still willing to be listed as third-party mirror and so they fixed the issue they had (thank you !)

Some other people replied with a "sorry, we can't host a mirror anymore" answer . (Thanks for having replied my email and thank you for having been part of the successful "centos mirror party" !).

For the "unanswered" ones, I've decided that it was time to launch a "Spring clean-up operation" in the mirrors DB/Network.
I've removed them from the DB, meaning that the crawler process we use to detect bad/unreachable mirrors will not even try anymore to verify them.
We actually have more than 500 external (third-party) mirrors serving CentOS to the whole world, without counting the 50+ (managed by CentOS) servers used to feed those external mirrors, and sometimes serving content too for countries less covered.

Thanks a lot for your collaboration and support ! We love you :-)