This is at least a sign that you have to be careful.Ask specific questions and check if you receive answers on these questions In case you are using an Agency with email forwarding or other mail-services, and your correspondent is not responding on your specific personal questions, this could be a sign of being suspicious.
Write a detailed introduction letter (preferable translated in Russian), to receive a detailed reply of the woman If you write your Russian lady for the first (introduction letter) time, please write a detailed letter about yourself.
For the woman it's important to see that the man who is writing to her is serious about finding a new partner.
Check the agency If you visit the website of some Dating Agency, try to read all the information about this website before you start to browse through the ad's.
Perhaps their introduction or 'About-Us' pages or other relevant pages could give you some background information of this specific Dating Agency, which could give you a 'good' or perhaps 'wrong' feeling about this site and their services.
By the way I know a travel agency here, that can organize the trip to your country very quickly. if no, then put these words right above your computer, in case you will receive a letter similar like this.