Why can't I view emailed pictures in my yahoo account, but can in my gmail.com account?

maybe a problem with Yahoo!
Why can't I view emailed pictures in my yahoo account, but can in my gmail.com account?
We're sorry. The Yahoo! Mail servers are down and will require a maintenance period. However, it might have been your fault. Please try again in 24 hours using a different method of attachment and/or a different file type.
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