Several of our members use Apple Macs and have experienced problems with their images being automatically resized when they email them for competitions or evaluation. While I have no experience of using a Mac, a colleague of mine does and I asked him to help me figure this out. Here are the conclusions we reached.
Do not use the emailing feature of your image management program.
Resize your images with your software of choice and save them as copies (you don’t want to overwrite your originals) to JPEG files with the correct image resolutions, file sizes and file names (guidelines here). We have a how-to showing how the resizing can be done in Photoshop.
The steps and screenshots below are from Mac OS X 10.11 “El Capitan” If you are using an earlier version of OS X the steps should not be too different, though the apps may look a little different.
In the new mail editor, address the email to firstname.lastname@example.org, enter a subject and any text you want, Then click on the Attach icon at the top right.
In the file chooser dialog, click Options at the bottom left if you don’t see the Send Windows-friendly attachments option.
Make sure that Send Windows-Friendly Attachments is selected.
Select your photo and click Choose File. Hold down the Cmd key when clicking if you want to select more than one image.
Select Actual Size for each image you have attached before sending the email.