If your firewall is blocking the domain name that Carnival uses for the email specials, then there is nothing THEY can do about it. They will not change their sending email address. The probelm would have to be addressed on your side. MOST firewall software allows you to see the blocked emails and let you decide if they should be allowed through. Or, if you have a system adminstrator, you could ask them to "unblock" the sending email domain (sometimes they will say "No" to this request)Without knowing more info on your situation (work or home computer and firewall software) I can not offer more than to find out if you can see the blocked email. Then you SHOULD be able to mark the Carnival email addresses as a "trusted sender"
IF you can not do that OR your firewall blocks any and all images or attachments (which seems sever but possible), then your only choice would be to do as suggested above and get a yahoo mail or google mail account and have them change your email address to that (which you can do online at their (CCLs) site in your account profile) Then you would have to periodically check that other email site which runs through a browser window and therefore would let you see the any pictures or attachments without them having to get through your email firewall.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013