That sounds like Mail. The baseball is one of Apple's default 'profile pictures'. You can change it to an image of yourself, or just a picture you like (Apple offers a few, or you can add anything).
You could go to System preferences > users & groups, and then click on the picture and change it to one of those offered by Apple, or any recent image or photo, or even a grab from the camera at the top of your screen.
Apparently these images don't appear on the recipient's email.
Another way to change an image that appears in Mail is to go to contacts, select a contact, click on the image (or the place where the image would be) and add an image. Again, I don't think that an image you choose to be associated with you in Mail will appear on the recipient's email. The image associated with a contact is what you choose, not what they choose.
This thread is now locked and can not be replied to.