// Generate a random string
private static string getRandomString(Integer len) {
    final string chars = 'abcdefghijklmnopqrstuvwxyz';
    string out = '';

    while (out.length() < len) {
        Integer idx = Math.mod(Math.abs(Crypto.getRandomInteger()), chars.length());
        out += chars.substring(idx, idx+1);
    }
    return out;
}

List<Account> acctList = new List<Account> {
    // Dummy account
    new Account(Name='DO NOT DELETE', Email='test' + getRandomString(5) + @mailinator.com')
};