If you are receiving these in Outlook you may have to add the originator in the Outlook Trust Center.
Also see the previous thread about this: Imbedded Image in Email
Where I responded with
Did you look into the Junk/Junk Email Options/Safe Senders? Try adding your originator address there and see if it makes a difference. If it does you could check if it's possible to get the originator email address added as a trusted sender through the group policy or other distribution method throughout the company. Perhaps it's enough for it to be in the global address book if the "trust contacts" option is used. You could also try to link the logo from an inhouse content-server if you have one.
Brandon has not yet verified if that solved the issue, but it could be worth trying.
Br,
Per Christian
