We live in a generation where even some of the nicest people routinely ignore emails [not only the mass ones but those sent by friends who are awaiting a reply] and screen telephone calls, ignoring those in instances where they don't see themselves as benefiting in some way [in a fraction of a second our mind is able to determine whether we want this communication or not, factoring all of the different variables - who it is, what our relationship is, how busy we are etc. etc. מה רבו מעשיך השם that we can make calculations so fast - much faster than any computer].
ממה נפשך - If I want to speak to this person, then I would have called him [or her - women are more sensitive so it is a bigger aveirah to pain a woman] myself. If I didn't call him that means that I have no reason to want to speak to him. It must be that he needs something from me. So I can ignore him.... Unless I have some stake in the matter [e.g. it is my father and I have an obligation of כיבוד אב. It is my boss and I want to keep my job. It is my wife and I want to stay married....]
The only way people are able to do this is because the person they are ignoring is not present. If the person were here then nobody ignores someone talking directly to them. But what does the Jewish code of good middos dictate??
I sometimes think that when a Jew davens, Hashem says - "You ignore my sweet children when they want to speak to you, so why should I listen to YOU".
I know somebody who basically decided to stop calling and emailing people [and he doesn't have whatsapp or a phone that texts]. He just got tired of being ignored....
Here is a BEAUTIFUL LETTER from HaGaon Rav Shimon Shkop to HaGaon Rav Y.M. Charlap [from the wonderful sefer Zeved Tov, edited by Rabbi Ari Zahtz] where he profusely apologizes for not responding earlier - with a "Shkop-esque" lomdishe knaitch.
Zchusom yagein aleinu!!!