Mailman on DH to gmail bounces

I am running a list serve on DH using mailman.

It only has 5 users on the list. We all use the gmail platform for email.

Very frequently - gmail servers identify mail from the list as spam and bounces it. That results in mailman setting the subscriber to NO MAIL status.

At that time, mailman sends a link to the subscriber - to click on which takes him from NO MAIL to MAIL and all is ok for a while… until the cycle starts again.

We have made filters on our gmail web UI to never flag mail from the list as SPAM.

One user states it doesn’t work, because he was again set to NO MAIL by MAILMAN again for bounces.

DH support sends me to a gmail help section on google - that is really no help with this issue.

Anyone have any ideas?