It’s common knowledge that nearly all email programs have trouble with huge files. So to stay on friends and family good sides, follow these tips for downsizing your photos for email:
1) When you are e-mailing or posting a photo, aim for a JPEG file size that ranges from 50 to 100 kilobytes. (Remember: When resizing photos, always save the resized image as a copy, or use another file name, so you do not overwrite the original. If you want to print photos later, you will get far better results with that high-resolution file)
2) To resize an image in Photoshop Elements, open the photo and click Image, then Image Size. After ensuring that Constrain Proportions and Resample Image are checked, change the resolution to 72, then enter a value in the pixel-dimension size box — the other value will adjust automatically. For instance, enter a width of 800 pixels to resize a three-megabyte photo to a size of roughly 100 kilobytes. To make it smaller, click Save, then move the Quality slider bar toward Smaller File.
3) There are also options do resize your images in both Windows Vista and XP as well as Macs default photo programs preview and iphoto (these usually involve right clicking, choosing “save as” or using the built in email buttons, read the article for full step-by-step directions)
4) And of course there’s the Internet: all the big photo-sharing sites: Flickr, Picasa, web image-editors such as Snipshot are good places to start. Even social networking sites such as Facebook offer options for sharing entire albums even with non-site users.
Read all the details of how to resize your photos for sharing at The New York Times.