Jenda,
I check upcoming birthdays everyday and send a Happy Bday /msg to the monks provided they have logged in within the last few months. I have never received a "please do not do this" reply. Mostly, I hear nothing at all, a few thank you notes, and one or two "I forgot all about that". The last, in at least one case, was followed by removing the birthday tags from their homenode.

Personally, I like the fact now that it takes effort to /msg someone to mention a upvote or a downvote. I have received a few personal thank you notes. I have also received a few "I believe you meant x on node ###". I was greatful for those - the effort made them that much nicer. On the other hand, if I were more prolific and there was an automated way to do this, I am betting I might begin to consider these notes spam. Furthermore, I would the ability to automatically delete them or not receive them at all. Then there is the "did you get my /msg about xyz?".

Again, I might be wrong, but I believe the value added doesn't outweigh the effort.

Cheers - L~R