All you need to do is go to YouSendIt.com and upload your file (the TIFF will do, perhaps throw it into a ZIP file first) and then the recipient will get an e-mail message explaining how to download it.
You could probably put your own mail address in as the recipient and then forward the message on, so your family or friends will know it is from you.
It's rarely a good idea to send anything more than about 5 MB to someone. There's a growing chance that they might be using some 'mobile' device, and could be charged up to 6 quid per MB (O2 rate for someone outside Europe).
It's generally better to save the file on ISP web space (or other free web space) and let the intended recipient(s) know the file(s) are available for download.
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When I worked for a consultancy they planned to send 100 MB of files to 3 different people in Spain via e-mail. It was (a) going to make their mail server crash, (b) would have taken hours to send via their ISDN connection (before 2000, no broadband), (c) cost a fair amount because of the duration of the dial-up call.
Simple solution was to ZIP the files and upload them, then send the three people the list of files so they could download only the individual files wanted.
It allowed persons A, B and C to download different files, and choose the most convenient time to do so.