Change certificate of no standard port

generate a new one and copy (with root user)

certbot -d mail.domain.tld --force-renewal --preferred-chain "ISRG Root X1" --manual --preferred-challenges dns certonly
cp /etc/letsencrypt/live/domain.tld/privkey.pem /opt/zimbra/ssl/zimbra/commercial/commercial.key
chown zimbra:zimbra /opt/zimbra/ssl/zimbra/commercial/commercial.key
wget -O /tmp/ISRG-X1.pem https://letsencrypt.org/certs/isrgrootx1.pem.txt
cat /tmp/ISRG-X1.pem >> /etc/letsencrypt/live/domain.tld/chain.pem

copy to tmp

/etc/letsencrypt/live/domain.tld/chain.pem /tmp
/etc/letsencrypt/live/domain.tld/cert.pem /tmp

Verify cert

/opt/zimbra/bin/zmcertmgr verifycrt comm /opt/zimbra/ssl/zimbra/commercial/commercial.key /tmp/cert.pem /tmp/chain.pem

Deploy cert

/opt/zimbra/bin/zmcertmgr deploycrt comm /tmp/cert.pem /tmp/chain.pem

Restart zimbra

zmcontrol restart