Hello and thanks again for your patience and updates.
I see you noted the date of June 2007 as the latest update for your printer. As it turns out HP's latest update released was October 2007.
That download includes: the HP Photosmart driver, HP Printer Utility, and HP Photosmart Studio imaging software for Mac OS X v10.3.9, v10.4 and v10.5.
(If you click the link below and it does not open, simply copy and paste the link in your web browser)
* HP PHOTOSMART C5280 DRIVER UPDATE 10-26-2007*
I admit I was surprised that this version is the latest driver for your printer from HP considering we are already into 2009, but is an update nonetheless and it does support 10.5. which believe it or not, the June 2007 drivers only supported 10.4 but still worked for the earlier versions of Leopard.
The 10.5.6 update for your Leopard OS was released from Apple, December 15th 2008.
I am not sure how long this issue has been occurring for you with being able to not print your email, but I can say sometimes Mac OS X updates can affect performance of other devices sometimes. This is where 3rd Party manufacturers like HP are supposed to update their Mac OS X drivers for their printers with the current version of Apple's latest Mac OS X platform. This however, does not always happen in a timely manner.
I state this only because, from my extensive experience of troubleshooting various brands of printers, no matter what is done, no matter how the printer is connected to your Mac, if the drivers are not updated by the manufacturer, this can affect the printer, in ways that it may work some times for some applications, but not all the time, as the printer is supposed to.
So I would like you to update to the October 2007 driver for your printer and see if this changes the way your printer functions when printing out your emails.
If it does not my next recommedation is to come back to this email and click this link:
I will still be here to assist as much as needed until you get resolution on this issue. However the link above is for you to contact HP, where you can either chat or call them and inquire if there are any newer updates for your printer being released to work with the Mac OS X 10.5.6 Leopard update.
Please keep me posted. I am keeping my fingers crossed that this updated driver will be the fix we are seeking.