Before beginning the comparisons between those; This new feature is exclusively for our Allies membership. You need to sign up in allies to use this glorious mailing system.
Anyway, previously we had many issues with Gmail and random spamming issues, that squeezing us to hell. Our many customers emails spammed by google without any reasonable reason. And many of them had troubled by contacting with us by ridiculous issues of google. So that's annoying and problematic for business.
We decided to create something far precious for our allies called CA Express. 
It's simple without those nasty bugs. So you can use your own email without spamming by google.
If you use the old fashioned way to contact with us, we might not see your email, even if we see, it may take longer to answer.
With CA Express you earn more respect, so we're looking exclusively at your request, faster and more efficient.
Don't you remember you are one of us now!!
We'll take cover of each other, just like now.
Check it out!!