Darla says:

So there was an error in Mark's address. If you want to write a regular letter to him, or send him a package, this is the correct address:

 The address is 

Elder Mark Helske

2005 N 900 E 

uru-mon unit 188

Provo, Utah 84602 (This was originally 84604, but they just changed it)

That's unit 188 not 180

Also, his email is mark.helske@myldsmail.net

Please let him know you are thinking about him and praying for him.