I need to send a bunch of HTML emails with a binar y attachmend and it would be easiest if I could do it from the command-line.<BR><BR>I know that I can easily send emails w/ attachments using "mutt ...

yep, that's my question. can I just create any .html file with html/css/pictures/links, and insert the code into an email using an email client (in my case, Apple's Mail.app on MacOS X Tiger 10.4), ...

Many people are sending HTML e-mail for no obvious reason or benefit. HTML e-mail can be recognized by colored backgrounds or typefaces. It sometimes has designs or other decorations in the messages.