[Bglug] gmail help

[Mr. CC]

Hi all,

I am trying to set up my new gmail account for only one very specific
contact they do not use encryption and will not.
I do not want to use Thunderbird for this account.
I have tried to find a way to allow only my contact list to e mail me,
without luck.
Is there a place in gmail I can select by e mail address who I want to
be able to e mail me, I looked at filters but am unsure how to use it.

all suggestions welcome

Thanks
Chris.