Good topic. When Hurricane Harvey hit, we paused communication to those in the Houston area as this pause was region-based and many offices were shut down and unable to even receive email. 9/11 is a sensitive subject, but I believe it is mostly industry-based. For example, sending communication to military or government organizations should be paused as they may be shut down in remembrance, but not necessarily to a software company just because they are based in Manhattan. Again, it is entirely at your own discretion.