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This is something that I consistantly wonder about when I send an email that includes attachments.

Say I'm working on a Word document and I want to email it to some co-workers. I open up Outlook and click the Attach file button to attach my Word document to the email. However, before I click Send, I realize that I want to make a last-minute change to the document, so I quickly switch to Word and modify the document, and then click Save. Do I have to remove the attachment in the email and re-add it? Or will the newest version be sent?

Essentially, I'm asking if Outlook will cache a copy of the file to be sent with the email as you're composing it.

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up vote 2 down vote accepted

I don't really know, but I'm confident to say that, yes, it seems like does cache them.

When I compose a mail and attach a file. I can then delete that file from my hard drive and the mail is still sent fine. I will also receive the mail with the attachment intact.

This leads me to the conclusion that the file must be copied as soon as I attach it.

By running Process Monitor, we're even able to see where the file is copied and how:

enter image description here
click to enlarge

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This sounds reasonable. I always err on the side of caution, but it's something that's good to know. I'll accept for now. Thanks! – Ben Richards Aug 14 '12 at 17:25
@sidran32: I added more evidence ;) – Oliver Salzburg Aug 14 '12 at 17:30

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