Bitcoin wrong address
From the bitcoin wiki:


  Several of the characters inside a Bitcoin address are used as a
  checksum so that typographical errors can be automatically found and
  rejected. The checksum also allows Bitcoin software to confirm that a
  33-character (or shorter) address is in fact valid and isn't simply an
  address with a missing character.


In other words, your wallet shouldn't let you sent coins to a bad address, and servers won't accept the transaction.