@Gurudas
Glad to see you find this command.
You could add those information below to that command, in this way, you don't need to confirm. Even if there is a problem with one mailbox, the script can still be run for other users.
import-csv c:\temp\123.csv | foreach {Add-DistributionGroupMember -Identity "contoso_India" -Member $_.email -Confirm:$false -ErrorAction SilentlyContinue} -whatif
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