Q. Does one have to stand and honor a Rabbi, parent or elderly person when he is seen through a window, a glass or plastic partition in a shul (Mechitza) or a mirror?
A. Horav Chaim Palachi zt’l in Zechira Lechaim (Behaaloscha) mentions that one is not obliged to stand for the ones he has to honor, even when they are close by (four Amos), when they are seen through glass or a mirror.
However, Hilchos Ketanos (1: 274) disagrees and rules one should stand.
Horav Shlomo Miller’s Shlit’a opinion is that since the parent and offspring are in different domains, even if they can see each other there is no obligation to stand.
Rabbi A. Bartfeld as revised by Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a.