Here is the steps to backup individual domain on Plesk. I’ve tested. It works.
1) backup the domain
#pleskbackup -v domains yourdomainname.com backupfilename.bkp
2) Then create a map file
#pleskrestore –create-map backupfilename.bkp -map yourmapfilename
map file should be like that below. if not, edit it.
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++
[thisdomain’sclientname] # Client account name
yourdomainname.com 11.22.33.44 # IP address
mysql::@localhost:3306
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++
Then you can restore it with the following command.
#pleskrestore –restore backupfilename.bkp -level domains -map yourmapfilename
This backup will back up everything including mailboxes and database.