about the kernelnewbies email signature

[Chan Kim]

Hi,
How come some people's email contain the email signature shown below
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
.. while my email doesn't have it attached?
Are those people explicitly inserting it? or is there any option?
Thanks in advance.
Chan

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