My organization is in the middle of a process to move their Exchange 2010 messaging system from one archiving platform to another. As part of this process, we need to restore all archived messages back into users' email accounts, and then let the new system import them again. The problem is that when the messages are dumped back, the modified date on the message is set to the date it was restored, which trips up message archiving and basically means nobody will have anything archived for six months.

So you don't have to ask: no, our archiving platform only uses the modified timestamp on the message and cannot be altered to temporarily use the sent or received timestamp instead to determine whether to archive it. We and others have asked for the feature, but it doesn't exist right now.

What we're looking for is a method to go through the user's mailbox and alter the modified timestamp of each message (or preferably received more than X months ago) to the received date of the message. We also don't want to spend more on this tool per user than we're spending on the archiving solution in the first place. We've run across a few tools that are something ridiculous like $25 per user. I don't think we're even paying close to that for Exchange and the archiving solution put together.

Whatever we settle on should function on a live mailbox with no downtime. Playing around with PST imports and hacky little things like that isn't going to work.

We're fine with programming/scripting, if anyone knows the best way through PowerShell, COM automation or some other way to best handle this.