In my humble opinion YES. I regret that my sponsor never wrote to me not even as a group mailing but my Co sponsor and two of my upline team members did write me in both individual and group mailing. My Co sponsor welcomed me to SFI and looking back on it now I feel that I am valued as a person and not just one of the bunch.
I think that an ecard is even better because it even has nice pictures that get more attention than just words.