login as zimbra user

su - zimbra

change proxy mode

zmprov ms YOUR.DOMAIN.HERE zimbraReverseProxyMailMode redirect

restart zimbra proxy

zmproxyctl restart

check - if now listen 80 port

lsof -i tcp:80

Here is a basic restore procedure using fsarchiver for the same hard drive but a change went bad:

Boot systemrescuecd - if you installed the iso from omv-extras, it will be in your grub menu.
Mount your data drive - example: mount /dev/sde1 /mnt/backup
Figure out where your backup file is. fsarchiver uses the .fsa extension - example: /mnt/backup/omvbackup/backup-omv-07-May-2018_10-36-31.fsa
Figure out what your OS drive root partiton is. Don't get this wrong! - example: /dev/sda1
Restore the files - example fsarchiver restfs /mnt/backup/omvbackup/backup-omv-07-May-2018_10-36-31.fsa dest=/dev/sda1
reboot

Here is a basic restore procedure using dd for the same hard drive but a change went bad:

Boot systemrescuecd - if you installed the iso from omv-extras, it will be in your grub menu.
Mount your data drive - example: mount...