Sending your client an email with a large file attachment is often not permitted, considered rude, or could overload their account. There are a lot of ways to transfer or store large files for others to retrieve. I really like Onehub. It is very easy to upload and send files. It includes download confirmation, a secure location, and you can customize the page where your client will download the files with your own logo and color scheme. They have a tiered pricing plan based on storage/transfer capacity.
This post was originally published in September 2010. It has been updated for relevancy and accuracy.