Others can't open my rtf-laden emails correctly

Actually RTF encoding, and attachments are all formats which don't lend their way well for e-mail. There are so many different standards for e-mail formatting, it is a wonder that any e-mail programs are compatible with anyone else. At least in Mac OS X 10.4, you do have the option to use "Windows Friendly Attachments" when attaching via the attachment toolbar icon (which can be added by customizing the View menu -> Customize Toolbar). When you click on that toolbar icon, a dialog with the available files comes up with a checkbox to make the attachment Windows friendly. That should at least solve most of your attachment issues. As for RTF, HTML e-mails etc..., if you must send formatted information, it is better if you put it up on a website, and refer to the file's link on your e-mail than try to embed it in your e-mail. Simply ask for when the file has been received, and then take it off your website.

I am sending and rtf-enhanced email that includes 8
attachments.

In Tiger you are actually sending html, not "rtf," even though it is called "rich text." You might be better off formatting your message as a web page, opening it in Safari, and using Safari's "send page as email" option.

As for the question marks or other odd characters, that's an encoding issue, and this note may help:

http://homepage.mac.com/thgewecke/woutlook.html

Well Tom, I just have state my skepticism about this.

First off, HTML e-mails have in the past been used to phish people for information, and people block HTML e-mails or choose not to view them for that reason. So if you are sending an e-mail in HTML, I still say it is better to send a link to a website, or the file as HTML file attachment than to send it as RTF. Unless you are in communication with the recipient and know exactly what e-mail client they are using, it is better to assume they aren't going to be viewing HTML or RTF e-mails than viewing them, just because of the problems of phishing via spam.

Personally I think email should be confined to plain text. But a rather huge number of people seem to consider that sending html email is essential for them.