A Florida HOA is in breach of contract: the next step is to send a 'demand' letter seeking actionable remedy. There is a history with HOA of using email: is there any compelling reason to send the demand letter via USPS registered mail?
Why use USPS to Deliver Demand Letter when email is available
The answer essentially lies in NateEldredge's comment, and is consistent with Firefighter's Inst. for Racial Equal v. City fo St. Louis, 220 F.3d 898, 903 in that regular mail (and impliedly email) as a method of service is generally inadmissible "because the court cannot be assured that delivery has occurred".
Even if the HOA replied to your email, phoog is right in that the possibility of falsification of email records may prevent some courts from admitting service by email.
in some jurisdictions and circumstances e-mail is insufficient.
In germany an e-mail does not constitute at all to being in wrtiting ("schriftlich/Schriftform"). Several types of actions necessarily requires things to be in writing, which the law requires to be on paper, signed, and affixed to the paper in a manner that can't be easily altered ("Dokumentenecht"). A pencil note wouldn't be "in writing" as a result, because pencil isn't "Dokumentenecht".
Among the things that have to be in writing are notices of quitting or firing from a job, as well as changes to rental agreements.