Common names are priority targets for brute force attacks. Avoid creating email and account names including words listed below. The data has been collected from a vast number of attempts, chosen the most frequent ones, plus some random sampling. Ironically, pretty sure these keywords will only attract more spam, but I hope it helps someone.
PS: Also avoid using your domain name or obvious abbr. for your domain name in your accounts.
admin
webadmin
test
test1
public
demo
ftpuser
ftpadmin
contact
testuser
upload
root – obviously
administrator
info
support
sales
recruit
guest
backup
postmaster
anonymous
marketing