First, don't send any personal info for screening until you've corresponded with the girl, and have ascertained that she's available and willing to see you. That way, you won't have to worry. Something like this: 'Hi Miss So and So, I found your ad on Eros and would love to schedule an incall appointment in Boston for 2 hours, either Thursday or Friday this week. I have perused your website, and am completely willing to be verified. Before I send my info, I just want to make sure that you are available on the days/locations I am requesting, and that you're willing to see an older guy.'
If she doesn't reply after, say, 24 hours, then I'd send her a second email - 'Hi, I sent an email on Thursday and never received a reply. I wasn't sure if you'd received the original message, so I just wanted to follow up. As I said, I'd like to meet [here] on x or x day, or maybe next week if you're not available on those days. I've looked over your site, and am more than happy to provide the screening information you ask. Hope you have a nice day.'
If she doesn't reply to that, then move on.
As to why she would just ignore an email, that's a bit more complicated. I used to answer all emails, even if just to direct them to my screening form, or politely say that we wouldn't be a match. I found that, rather than 'respect my wishes' as I asked... the dudes would BOMBARD me with emails, telling me, 'Seriously,you really want to see me, I'll make your day. I PROMISE!!!' I'd then ignore THOSE, but sometimes the guys would keep it up for months, sending emails on a daily, weekly or semi-weekly basis. Just really strange, and made me anxious.
On the other hand, if I stopped worrying about appearing rude, and gave myself permission to ignore... the guy would email me maybe one or two additional times, and generally give up after that.
What I decided, was that if there's a chance that someone might be a problem... it's best just not to engage. Even minimally. It seems to encourage a certain type of guy (read: the type I do NOT want to see). I realize that it seems rude, and I'm sure I've ignored a few guys who may have turned out to be OK. However, it's the best way I've found to keep things drama-free... and it keeps me from worrying at night that one of those persistent f***ers will turn renegade.
But, you're in a great market with a lot of providers. If one decides that, for some reason, you aren't for her... then there are surely many others who will be very happy to meet you.