It does not sound like the judge did anything wrong. If you use a PO Box for the address in a Three Day Notice you have to provide an additional five day period for mailing the payment. Your case has been dismissed. You need to serve a proper three day notice and file a new eviction. If you only allow cash in person payments, then you must provide a physical address where the tenant can deliver payment. You cannot use a PO Box if you will only accept cash.
No attorney-client relationship is created by answering questions in this public forum. If you wish to create an attorney-client relationship, you must contact me directly and sign a representation agreement. Answers are provided based on general ideas and an answer specific to your situation would require a review of all documents.
Eviction can be tricky. It is difficult to understand the loopholes that allow tenants to stay in the property. Rather than trying to do evictions by yourself, you should hire an experienced real estate lawyer in your area to represent you.
Disclaimer: This answer is provided for informational purposes only, does not constitute legal advice, and does not create an attorney-client relationship. Actual legal advice can only be provided after completing a comprehensive consultation in which all of the relevant facts are discussed and reviewed.
My advice is to do the following things immediately:
1. Go to your nearest bookstore or Amazon.com and order: "Florida Landlords' Rights & Strategies".
2. Sign up for your local landlord organization OR if you cannot attend local meetings, sign up for a landlord association and use their online resources.
3. Hire a local landlord lawyer to go over your mistakes with you and issue a new three day notice to be served immediately. (3 business days *plus* five if you mail the notice *plus* five if you use a post office box)
4. Decide if you just want the property (Count One for Possession) or if you want possession and money damages judgment (Count One for Possession and Count Two for Money Damages Judgment). If you want a Count Two, then remember that the defendant-tenant MUST be personally served. If they avoid personal service, it is handy to know where they work and where they move to after they leave your property. Don't go to their job or harrass them, just keep your documentation handy and take notes on where they may possibly work.
The judge was absolutely right. The law (which includes both Florida Statutes on the books AND case law, which interprets the statutes) clearly says that the Three Day Notice must be done right or the entire case will be dismissed. You may want to attend eviction court and observe for a day or two. You can call the clerk of courts in your jurisdiction or a nearby county and observe.
Good luck. It is very frustrating to comply with the laws as they seem weighted in favor of the tenants at times. However, we have to follow the law as it is now, not as we wish it to be.