I have a real estate investor customer who will not answer the door for the mailman to accept my certified U.S. Mail letter of Notice To File Mechanic's Lien. The work was completed about 90 days so I have 30 days left to file. I have proof that the customer viewed my final Quickbooks invoice and also viewed the Notice Of Intent that I had attached exactly 10 days ago, ZLien also sent me proof that the customer opened their email 10 days ago and viewed the Notice Of Intent. Illinois law sounds pretty clear that the notice must be received by certified U.S. Mail, I'm prepared to file the actual mechanic's lien this Friday but I don't want to waste money if my mechanic's lien won't be valid in court if it goes that far. To make matters worse, my customer has the house up for sale and realtor open house every weekend, this house is going to sell fast and I feel that I need to act very soon or I will never see a penny of the $6800 that is owed to my company. Any advice would be greatly appreciated!