I use the Deferred Send Message Option very frequently.  For some unknown reason this week my Outlook *.ost file has become corrupted.  This file was kept locally on my PC in a cache file.  An outside IT service we use, explained to me that I closed Outlook before it finished updating with our Exchange Server.  Long story short,  from our Exchange Server they placed a new cache Outlook file locally on my PC.  But, I find out, that all messages in the Outbox are stored locally and not on the Exchange Server.  Any ideas on how we might get the information, out of the old Outbox.  We had renamed the old file as outlook-old.ost file.

Look at ExMerge as a possible solution. This tool can import data from a pst file directly into a mailbox. Make sure you run ScanPST on you pst file before you use ExMerge.

For work with mails advise use-

view ost file,

as far as i know tool is free and has many features,it "allows to recover *.ost files, when Microsoft Exchange Server gets out of order and your data may be lost,open damaged files, you can open your corrupted *.ost file and estimate data losses,can convert *.ost files to *.pst files, that can be easily opened by any email client, compatible with Microsoft Outlook,convert your *.ost to *.pst, but to extract a list of files in such formats, as: *.eml. *.vcf and *.txt,allows to view a ost file and avoid extracting, for example, 50 Mb of your content, you can extract all files from .ost viewer mail, than just to copy and paste emails and contacts, that you need,view ost file runs under all versions of Windows operating system, such as: Windows 98, Windows Me, Windows NT, Windows 2000, Windows 2003, Windows XP and Windows Vista.