If you look at each post, then you will also notice that the box clearly state who has said what.
Even if I don't sign this Post with Rhutobello, you will have little trust that other members then me has posted the answer....because only I have the "voice" or "key" to display Rhutobello on the side....just like you can almost can be sure that your post display Krishnakumar M R.
When we sign post, then we can do so because we feel it is the right thing to do....or if other family members use our account to post their view.....which then not necessary must be the account owners view.
As for email...pm...or more personal interaction, then I always use my sign.
As for Hello.....we have the intro forum where we hope new members introduce themselves and say hello.....to say hello in each post will be overdoing...and I think a bit annoyance in the end.....but if one step in as a new member it will be fine if they do it. ....
In short...do what you feel come natural for you...I am sure most other do the same.
Life creates life.....even "small talk" is better then "No Talk".....but I agree....to Much "Small Talk" can repel members who want a more serious approach to our subjects....so we urge you all to start topic that is close to your hearts
