URGENT! renewed LE cert is not working on iphones

Our letsencrypt cert expired today but did not auto renew. Per the following post I ran:
sudo certbot delete --cert-name mail.mydomain.com

https://www.howtoforge.com/community/threads/letsencrypt-error.86205/

)I had to run certbot twice)

Then I had reports that iphone users couldn't get mail and was getting a cert error. The cert shows up as the old date 8/17/21. My outlook and android users are working. Is there a certificate used by the iphone that maybe didn't get copied to the right place?

 

I got an error (sorry didn't write it down) the first time I ran the certbot command mentioned above. so running the certbot command again did not produce an error.