This is a hard question to ask, people can create email domains easy. I own a domain simplelaughs.com and have the email domain: "User"@SimpleLaughs.com
I use help@simplelaughs.com
Maybe buy a domain starting with S is the best idea.
A bird that has 8 letters and starts with s is: starling or snowy owl.
Swaziland
salamander
Southern
Sole
SaggitaSaggitariusScorpiusSculptorScutumSerpensSextans
samsung?
supreme
skin
seal
scope ?
Shinto