Set-MailboxAutoReplyConfiguration -identity “[email protected]” –AutoReplyState Scheduled –StartTime“06/30/2014” –EndTime “07/02/2014” –ExternalMessage “Thanks for your mail. I am out-of-office and do not have access to mails. ” -InternalMessage “Thanks for your mail. I am out-of-office and do not have access to mails. “

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Set-MailboxAutoReplyConfiguration -Identity [email protected] -AutoReplyState disabled

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https://docs.microsoft.com/en-us/powershell/module/exchange/mailboxes/set-mailboxautoreplyconfiguration?view=exchange-ps

Enable Out of Office thru Powershell