Mailchimp is whitelisted but emails still not forwarded

Sorry cannot help you, you decided not to use our server for email. You will have to figure it out on your own.

I'm sorry, I don't follow.

We WOULD like to use the FTH server for email, so my question is what am I doing wrong with settings that prevents this from working?

Based on the info I provided, do you know what I need to fix to use the aliases properly again (as we've done for a few years) with our custom domain?

Remove all the google MX records and add the single FTH required MX
You can only use the email forwarders FTH provides. You might be able to do something with the email groups you will need to read the documentation.
We do not provide email accounts.

Generally speaking, in order to integrate FTH with third party service providers, you would enter one of the public officer email addresses as the registered email address for verification purposes. The officer email address should be one that forwards directly to you, so that you can complete any verification/confirmation steps for registering it. Keep in mind that all FTH email addresses are strictly distribution lists and forwarding email addresses--no accounts.

If you are not a club officer, the simplest thing to do is to just temporarily "make yourself one" in Membership Management. Users get all caught up in making sure that the officer settings actually match what is in reality. It is kind of overblown non-sense, since all you are really doing in MM is just effectively matching real world personal email addresses with the forwarding addresses (and dist lists) that FTH provides. You can change something temporarily (by setting an officer role) to be you to allow for a particular officer email address to be the one tied to a 3rd party service... just change it back once the verification is done and you have done the verification. With this approach, I have sometimes been every club officer in a club within a short timeframe.

If you do this, I *strongly* recommend using the club number version of the FTH email address. Clubs change custom domain names all the time, they expire, they change club names, etc. etc. If you use the club number version, you will never face an interruption because of future changes after you have moved on to other things. This is also why I tend to not recommend using custom domains w/ third party service providers. Custom domains are a "nice to have" and if you make too many things dependent on them, you are effectively setting up your club for future problems. We have seen this over and over again w/ custom domains --clubs always say "oh sure, we will certainly remember to renew it before the expiration date"... but today's commitment is not a guarantee of future club sentiments.

I found the issue. Google Domains has a separate "synthetic records" area where they hide the mail forwarding settings and thus all the Google MX records. I was able to delete those, which then allowed me to add the one MX record to my DNS settings.

I understand it could take time to propagate, but I expect it will work.

Thanks for guiding me to consider other settings I might not have found otherwise!