A few items for clarification please:
1. What mail program are you using?
2. Can other people receive pics from you?
3. Are you sending the pics in the body of the email or as an attachment.
I'm also tempted to ask how large they are - on the grounds that your ISP or hers may have a size limit imposed on the mail server. But
AFAIK, if the email is oversize, the whole thing gets dumped, not just part of it, so the envelope wouldn't show up in your friend's SysTray.