Florida Statutes section 83.49 states the process by which landlords or landlord agents can hold deposits after the lease terminates. Under this statute, "Upon the vacating of the premises for termination of the lease, if the landlord does not intend to impose a claim on the security deposit, the landlord shall have 15 days to return the security deposit together with interest if otherwise required, or the landlord shall have 30 days to give the tenant written notice by certified mail to the tenant’s last known mailing address of his or her intention to impose a claim on the deposit and the reason for imposing the claim." (Sec. 83.49(3)(a)).
Courts are likely to construe this provision strictly. Email is not generally a satisfactory substitute for certified mail, but courts may nevertheless accept email as a substitute if the signed agreement authorizes notice via email. However, if the landlord did not provide notice within 30 days, and in a statement similar to the form also provided in this section, then a court will likely find for the renter/lessee.
Under the statute, if the landlord or landlord's agent provided notice of intent to claim the deposit, then the renter has 15 days to object after receipt of the notice. Time requirements are critical -- even one day late is "too" late.
There are other requirements in the statute. Read the statute first before filing (if you file the action yourself in small claims court), or contact an attorney who can fully investigate your claim to ensure it meets with Florida law. You can obtain the statute's text at http://www.leg.state.fl.us/Statutes/. If you file the action yourself, read up on all of the statute sections in chapter 83 pertaining to residential tenancies.
If your situation meets with the statute's requirements, small claims court is a proper forum for resolving this dispute.