There are two ways to protect Lotus Domino with the current version of Backup Exec

Offline Backup

1. Shutdown the Lotus Domino services, either by enabling a pre-command within the Backup Exec backup job configuration or by running a task via Task Scheduler outside of Backup Exec.
If Task Scheduler is being used, ensure that all the required services are shutdown before the Backup Exec backup job is scheduled to start.
Refer to your Lotus Domino Administrator Guide as to which exact services need to be shut down.

2. Backup the data
Lotus Domino is dependent on the following files, which should be backed up. Please ensure these are being selected within the selection list of the backup job.
The following list is valid at the time this article has been written but additional files might be required, please refer to your Lotus Domino Administrator Guide for more details:

- Domino server data files 
- All databases
- Template files
- The notes.ini file
- ID files 
- Mailbox

3. Start the Lotus Domino services, either by enabling a post-command within the Backup Exec backup job configuration or by running a task via Task Scheduler outside of Backup Exec.
If Task Scheduler is being used, ensure that the backup job has finished before that task is scheduled to be run.

VSS Backup

When using the VSS backup method, it is recommended the following two commands be executed prior of the backup job running, to release all open sessions and close most files.

nserver –c “drop all”
nserver –c “dbcache flush”

This can be done by either enabling a pre-command within the Backup Exec backup job configuration or by running a task via Task Scheduler outside of Backup Exec.
If Task Scheduler is being used, ensure that the required services are all shutdown before the Backup Exec backup job is scheduled to start.

Lotus Domino is dependent on the following files which should be included in your VSS backup selection list.
The following list is valid at the time this article has been written, but additional files might be required. Please refer to your Lotus Domino Administrator Guide for more details:

- Domino server data files 
- All databases
- Template files
- The notes.ini file
- ID files 
- Mailbox

NOTE:
Veritas Backup Exec does not support Domino transaction logging.

Backup Exec no longer has a backup agent available for Lotus Domino.
For more details see:
Lotus Domino End of Life with Backup Exec 16
https://www.veritas.com/support/en_US/article.100033221 UMI Code: V-79-57344-3883 : Backup and restore operations for Lotus Domino are not supported by this version of Backup Exec.
Error Code : 0xE0000F2B