It may be a bit misleading to have NFL HOF in your subject, as Kurt Warner is not currently a member of the Pro Football Hall of Fame.

You can always send to an active player/coach/executive c/o their respective team, just not always in the off-season.

Brett Hull currently works for the St. Louis Blues, so you can try sending to him c/o their. You may have to wait until the season starts, as not all teams hold on to fanmail during the offseason, though seing as he is in the front office, he still may get it now.

Take a look in the database.

While you are certainly welcome to try the address that the admin gave you, keep in mind that Paige is on the main roster, and not the NXT roster.

I would suggest not posting your phone number on here. The odds are very slim of any celebrity seeing it, let alone contacting you.

New York City FC
600 Third Avenue
30th Floor
New York, NY 10016

This is the address listed on their website.

If I had to guess, the address the admin posted probably won't work, as I don't think that the Undertaker spends much, if any, time with the NXT roster. I would research that before you send anything.

It looks like they may have a website, maybe you can find something there for contact information.

I am not admin, but regarding sending to Toronto Blue Jays and Cleveland Indians, you can always send c/o the team; their is just no guaranteed success.