I think we talked about this the other day and I said that I myself am a construction worker and server.

R/C Mail is the best way to prove notice was served.....unless you hire a process server. :)

Ideally have a process server hand deliver.

it was happening to me last week. almost every time i'd click on "post reply", it would take me to a "server error" type page. when i go back and post, it would appear twice.i had a thread about it too.

Most most landlords when the rent is late do not first serve some kind of a notice with a process server.

Here is in Illinois, it is strongly recommended by most attorneys to use a server to serve any notices including 5 day notice. 

Legal notices can sometimes be delivered by Process Servers (private entities) instead of the Sheriff or other law enforcement. 

Unfortunately, I won't be able to provide much help if you are on another email server.

If you own the property in FL, you can do your own eviction and just pay the court costs, process server and sheriff.  

Well, for me I have used both products in serveral applications following the manufacturer's specifications without any of the issues that are concerns for you.