$ host stackoverflow.com
stackoverflow.com has address 69.59.196.211
stackoverflow.com mail is handled by 30 alt2.aspmx.l.google.com.
stackoverflow.com mail is handled by 40 aspmx2.googlemail.com.
stackoverflow.com mail is handled by 50 aspmx3.googlemail.com.
stackoverflow.com mail is handled by 10 aspmx.l.google.com.
stackoverflow.com mail is handled by 20 alt1.aspmx.l.google.com.