How do you set up hosts and custom routes IN g suite to get traffic to flow through to Office 365?

We are currently migrating from Office 365 to g suite for the majority of our users.
For now, we need some of the traffic to run through google and forward back to Office 365.

In gsuite, this option is Apps -> G Suite -> Settings for Gmail -> Advanced Settings
There are 2 sections that have to be setup.
Custom Route

Here is an article where they discuss this:
My guess is that I think I need to concentrate on the "Host / Add Mail Route" part.

I've attached the screen so you can see what it looks like.
The only guess I could make was to enter: : 587

For the custom routing, I'm telling it to use the host above and to send all email for -> (at Office 365)
When I test this, I get the following error:
The response from the remote server was:
530 5.7.57 SMTP; Client was not authenticated to send anonymous mail during MAIL FROM []

Does anyone have any suggestions? This seems like it would be a simple implementation because of all the Office 365 -> g suite and g suite -> Office 365 migrations that people are doing but obviously I'm struggling!

Thanks in advance!!
Randy AAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Try using the Office 365 MX host for your o365 domain which  should be port 25 ( find exact value for xxx in your o365 dashboard under Domains )

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Hi Randy , any luck with your issue?
Provided a possible resolution path, No feedback from author
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Microsoft Office

From novice to tech pro — start learning today.