When checking a file out directly to email this is essentially the same as a local check out of file except that you will first be asked to choose the recipients using the 'Communicating with other users' form.

When in Outlook mode the form also enables you to choose the type of message you wish to attach your checked out file to, so although email is the most common you could attach it to an appointment or a task for another user or group of users.  The alternate SMTP mode will only support send as an email.  The file is only finally checked out to you once you have pressed the OK button on this form.

A checkout to email is treated differently by the system which doesn't put the checked out file in your checkout folder.  This is because you have attached it to a message and sent it on and there should therefore be just one copy of it and you will need to get this back from the recipient at some point as the checkout is shown against you.  If the recipient loses or corrupts the file, or advises that no changes are required you can still use the Undo checkout  feature as you might have done with a normal checkout.

During Checkout any Office Export Properties will be updated in the file and then shown where the doc properties have been set to display in the file.

Additional functionality has also been provided to support return of checked out attachments for users in Outlook mode.