What is their complaint about email?
Alternatives are FTP, yousendit and other file transfer services. I often put stuff on my iDisk for others to download but this requires a small effort on their part.
The main problem with email is that the attachment size is usually limited to 10MB (some hosts allow more but some are even stingier). Another is that some companies restrict or block email with attachments for security reasons.
The best bet is to just ask them how they want you to send the files.
