Windows has a in-built feature of providing option for reducing sizes of the photos before sending them in a email as a smaller version. This would reduce the recipients time taken to download those images if they have a low speed internet connection. You can do this by selecting the photos that needs to be sent as an attachments and then right click and select Send To followed by Mail Recipient from the menu list.
This would display the following Attach Files dialog box provides users with option for choosing the size of the images.
Select the required size and click on the Attach button. This would the adjust the size of the photos to the selected Picture size and attach them as part of the email.