Can someone point out why mailx/gmail results in an Error?

Can someone point out why mailx/gmail results in an Error?

Based on various articles, we're testing Mailx from the command line
The test is running (Fedora/Centos). We run into the
Error in certificate: Peer's certificate issuer is not recognized.
Mailx is installed. Per articles, we're using the mozilla/firefox dir.
The command we're using from the cli is:
echo "test data" | mailx -s "test sub1" -S smtp-use-starttls
-S ssl-verify=ignore -S smtp=smtps://smtp.gmail.com:587
-S smtp-auth=login -S smtp-auth-user=abc -S smtp-auth-password=marsaa
-S from="aaa@yahoo.com"
-S nss-config-dir=/root/.mozilla/firefox/kbatbh5m.default/ bbb@yahoo.com
The emails go through/get sent, but we still get the certificate error.
The test is running FF 23.0.1, centos 6.
Any pointers to resolve this would be useful.
Thanks!!