It sure sounds to me like you have Photoshop setup to print to email as opposed to an actual printer. I don't have Photoshop so I can't provide specific instructions, but I would think when you go into the Printer setup in Photoshop there is the option to chose various printers, just pick the one that corresponds to the printer you have setup in Apple -> System Preferences -> Print and FAX.
I do have Photoshop here and see nothing regarding email. I'm curious how the poster is attempting to print the desired image from PS (File>>Print; Command + P, etc.)? Also, what version of Photoshop (or is it not PS but Elements or Lightroom)?
I'm thinking that either Elements or Lightroom has an "Email Photo" feature similar to iPhoto, however, since they're not integrated with X as the iLife (or even the iWork) apps are, they need to be configured for SMTP (since they probably use a built-in emailer rather than the system default). People constantly wonder why Adobe does some of the things they do, this would probably qualify as one of them.
From Photoshop Elements Help (The last line says it all):
Photoshop Elements enables you to share photos by e-mail. You can either attach photos to an e-mail or embed a photo in an e-mail using Photo Mail. You can also share online albums and share photos by burning them to a CD/DVD. Since Elements Organizer enables efficient organization and management of media files, you can start the share operation in Photoshop Elements and complete it in Elements Organizer. Elements Organizer enables you to select the required media files for sharing. The Share tab in the Photoshop Elements provides the following options to share photos:
Enables you to share the albums. E-mail Attachments
Enables you to share photos as e-mail attachments. Photo Mail
Enables you to use a wizard to embed your photos in the body of an e-mail message, with colorful custom layouts (stationery).