Indiana Code Title 32. Property § 32-28-12.5-10

Sec. 10. A broker company shall, not later than ten (10) days after recording a notice of lien under this chapter, personally serve or mail, by registered or certified mail, a copy of the notice of lien to the owner of record of the commercial real estate, or to the agent of the owner of record, at the address of the owner stated in the written agreement, contract, or other written instrument on which the claim for the lien is based.  If the address of the owner or the owner's agent is not stated, the broker company shall personally serve or mail, by registered or certified mail, a copy of the notice of the lien to the address where real estate taxes are sent for the commercial real estate on which the claim of lien is based.  Mailing of the copy of the notice of lien is effective when deposited in the United States mail with postage prepaid.  Personal service of the notice of the lien is effective upon receipt by the owner or the agent of the owner of record.  A broker company's lien is unenforceable if mailing or service of the copy of notice of lien does not occur at the time and in the manner required by this section.