I sent letters to approximately 30 to 40 ladies, I think, I am interested in them.

[petrov...@gmail.com]

I sent letters to approximately 30 to 40 ladies, I think, I am
interested in them. But I have a question. Will each lady receive my
letter ? I have fear, that the lady can automatically select on her
account, from which men (criteria like age, country...) she wants to
receive letters?

No, it is impossible for ladies. Ladies receive messages from all men
who write to them. But, of course, some of them check their mail
regurarly (each day or several times a day), while the others do it
once a week or even can be now absent on holiday. You can go to your
outbox and check which letters were read and which were not. And, of
course, a lady can answer you or - let us be realistic! - keep silent
since she does not like you.