Modern informality may have made people closer, but it has certainly created gender confusion. In the past, a person’s title in English included the obligatory Mr., Mrs, or Miss. Also, before the days of the Internet, ordinary citizens didn’t correspond with people living in places across the ocean and having interesting stamps. So, for the few people and few occasions when a writer had to address a correspondence to distant location, it was clear whether the respondent was male or female.
Today, we have created a global village of people addressing each other by their first name or at best by the first and last name, without title. Granted, the vast majority of names are clearly male or female in any language. Some languages make it easier by adding feminine endings to male names: Stephen / Stephanie in English; Jean / Jeanette in French; Joseph / Josepha in Hebrew; Yevgeni / Yevgenia in Russian. Knowing the rules often give the writer a solid basis to know whether to use the masculine or feminine forms of words when such a distinction must be made.
However, it is often not quite so simple. Sometimes, the writer is not familiar with the writer’s culture and does not know if the name is for boys or girls. Even worse, some names, such as Billie in English and Tal in Hebrew can go both ways. The worse situation is a name of a writer whose first name is only an initial, i.e. A G. Alexander.
One solution is to use Google pictures searching for the name in question. If 95% of the pictures indicate a specific gender, it is safe to assume to make an assumption. You could be wrong, but the person will probably understand. Just recall that Johnny Cash song A Boy Named Sue. Of course, it is always possible, albeit a bit clumsy, to ask the correspondent with words to the effect: I apologize for any embarrassment, but would you mind telling me if you are a man or women. The last option, granted a bit formal, is to write Dear Sir or Madam at the top of the letter and hope they understand.
Alas, those were the good old days….