One of the reasons we shoot pictures is to share our memories. And in Aperture, it’s incredibly easy to share your photos in a variety of ways; one of the simplest is through email.

The most obvious way to email a picture is by selecting one or many photos, and clicking on the Email icon. That’s fine if you know exactly what you want to send before you click the button. But sometimes you want to add a few photos, then add a few more, then add a few more, then realize that you’ve added so many that the email has gotten huge and you really should send these smaller. Dang.

There is a way to handle this that’s very, very flexible.

While the email button is great, you’re limited to the size that is preset in the preferences. If you want to send them smaller or bigger, you have to go into the prefs and change the setting each time. Mail.app (Mac OS X’s built-in mail application) can actually resize photos for you, but it can’t size them up—so if your preset in Aperture is set to small and you decide you want to send some larger photos, the you have to remember to change the preset before you hit the Email button.

The solution is as simple as drag-and-drop. By default, Aperture generates JPEG previews of every photo in your library at 1/2 the original file size—which is still a huge file! (To learn all about taking control of that JPEG preview, check out this free tip on reducing library size.) But you can take advantage of this big image when it comes time to email your pictures by letting Mail.app do the resizing for you.

In Aperture, select a couple of photos you want to email. Simply drag them from Aperture onto the Mail icon in the dock. Mail will launch if not already open, generate a new email, and add those photos to it.

Continue to add photos to the same email using OS X’s awesome Exposé features. (Not familiar with it? On the modern aluminum keyboards, it’s the F3 key, which has an icon that looks like a little rectangle with smaller boxes inside of it. If you’re on an older keyboard and don’t know your keyboard shortcut, you can open the System Preferences > Exposé & Spaces to control it. It’s the “All Windows” setting you want to use here.) Click-drag a photo or photos from Aperture, and without letting up on the mouse, press that Exposé key. All the open windows on your system will appear at once. Just drag the photos over the email window that you want to add pictures to, and pause for a moment—you’ll see the window flash, then come up full-size right under your mouse. Just lift your finger off the button and the pictures will be added into the message. You can keep on doing this to add as many files as you like to that single email.

But wait, won’t that email get huge, especially since we’re adding 1/2-size JPEG’s?! Yes it will, and here’s how you know how big that email has gotten.

Notice on the left it says this message is 2.0 MB? And that’s just with two photos attached! But also see to the right, there’s an Image Size option, which is currently set to “Actual Size”. Pull down that menu and you can choose from small, medium or large, and Mail will resize the pictures for you. You can even try all the settings to see which one gets you down to a size you’re comfortable emailing.

Here you see I’ve chosen Medium, and the message is reduced to just 134 KB!

You can still continue to add photos at this point as well, and Mail will automatically scale them down to match the rest.

This is a great way to control your emailed photos. You get to choose the size on a whim, and not have to think about it in advance. And of course you don’t have to resize the pictures at all, if you really do want to send that huge file!