The best way to stop needless pre-order messages from Clients is to build an independent online presence where you offer your Services as a Copywriter (preferably your own website), where you’ll firmly state that no one can message you before placing the order (sending you money) first, as your time is too valuable.
As a Seller on Fiverr however, you agree to Fiverr’s ToS, rules and mechanisms.
Fiverr allows buyers to contact sellers - as much as they want.
They encourage Sellers to respond. In fact, good response rate and time are one of prerequisites of being Level 1 + Sellers.
Therefore, as a Seller, by offering your Services on this platform you’re agreeing to answer those messages.
That’s the technical aspect of the issue.
As a Copywriter - you most probably know that when it comes to selling, it all comes down to perception.
In Buyer’s mind, as one of the Sellers offering services on a $5 Platform, your time is far from being valuable enough to bypass answering their messages. “If his time was so valuable he wouldn’t be here offering content for $5, and we wouldn’t be able to reach him at all”, is what they think.
This is why: “Please do not message me. I don’t have time to answer your messages.” is most certainly a terrible idea. It will most likely elicit a “why are you here then?” response coupled with, “why have you enabled me to contact you then?”
Sending such a message is not rude, per se. It’s delusional in a way.
It’s like an MMA fighter refusing to do a press conference before or after the fight. Yeah - it might fly once or twice, but soon enough, he’ll stop getting matches. Why? “You signed up for it, it’s a part of the deal. Even though you may not like it or feel its a waste of time that takes you away from training.”
It’s the same with Buyers messages. If you want to outgrow them - you simply need to outgrow Fiverr.
It’s that simple.