I've found each provider has her own style, what's important is how she performs in the session; but I know how you feel. I also like the flirty electronic contact before the show, this is a topic I've been struggling with on a personal level. I've had a wild ride in my first year, so excuse me if i go off....it's for my benefit too I guess..
First don't overdo it, they are running a business, they might be responding between clients, or if they're on a long date they might be responding while she or her date is in the bathroom. They get paid by the hour, time your self writing emails, it's a lot longer than you think, to them this is OTC time.
Sometimes it's a trade off, one of my favorites, a great talker in person, but normally responds to email with one or two sentences, but, .....she usually responds within an hour or two. If it's a more than several hours or a day she apologizes. Most of the other providers take a day or two, but they will engage in longer emails.
Make sure you are not looking for a relationship, that is not what they are providing. If you want an emial relationship try Ashley Madison. I joined for a while, I had one, it's was fun, it was drama with no sex, just like coming to Vegas is sex with no drama. Unless of course you make your own, excessive email and OTC contact is the first sign (yep, been there, done that, it sucks).
If you want a provider that is "electronically" chatty, find one on the boards, but understand that if that is your priority, you may not be able to find one that is e-chatty, and have certain hair color, breast size, weight, muscle tone, ethnicity, blah blah blah, that always makes up our fantasy. So don't look for a physical type first and hope you can request a personality from a menu, it doesn't work like that, personalities are not like lingerie.
Maybe you can post an ISO "Visiting in July, I like to meet a provider that will exchange one mail a week until we meet.". You may consider a little gratuity may be in order as well. What the hell, if guys can asks for girls into smoking fetishes, Greek, and daddy fantasies on this board, you should be able to ask for one that likes to share emials before a date.