I try my best to answer anyone who contacts me, whatever the communication medium. Even if it takes a number of months, I make a mental (and written!) note and it irritates me and I feel indebted until I respond.
Lately I had been thinking, why bother? Doing so detracts me from doing what I want to do and I could always choose to "forget". This was until someone mentioned to me in passing how he and others appreciated their being able to get through to me, and I thought "oh".
I felt really good inside after hearing this and couldn't understand why, until I stumbled upon this Hadith: "... The Prophet (SAWS) said, 'When anybody among you finds a good attribute in his brother, let him tell him of it, as it will give him encouragement to do good works'..."